Marlena finds Alice hiding; after she grabs the evidence written in Doug's blood, Marlena tells Alice to prepare to die.
Shawn runs into John at Celeste's and is shocked when John tells him that Marlena is the serial killer. Aware that the killer has systematically targeted the people closest to her, John urges Shawn to race home to Belle. Shawn's progress toward home is stalled when his car goes off the road in the storm - he must get out and run.
Belle soaks in the tub as Jan executes her plan to electrocute her. Belle has a fantasy about Shawn while she reads a romance novel. Jan gets the extension cord for Belle's radio and is about to drop the radio into the tub...
After encountering Sami and breaking the news that Marlena is the killer, Kate receives a visit from Roman's ghost and is grieved by the notion that Marlena is the one who took her husband from her.
John gets a call from Alice - Marlena is trying to kill her! John rushes to Alice's and has a collision with Sami's car. Sami refuses to believe Kate and John's assertion that Marlena is the serial killer and thinks that John is actually the guilty party. While John insists he is going to help Marlena and Alice, Sami thinks he is intent on hurting them. Sami grabs John's gun and holds him at gunpoint, determined not to let him harm her mother. As John advances, Sami pulls the trigger...
Outside Alice's house, Marlena wrestles with her conscience in the form of the ghost of Roman. Roman nearly convinces her to spare Alice, but Marlena is determined that she must eliminate her in order to prevent her family from knowing that she's the murderer.
Lexie visits Celeste and is stunned to find her mother unconscious on the floor. Celeste wishes she could remember what she predicted earlier tonight, before she was struck by lightning. Celeste finally manages to tell her daughter that Marlena is the killer. Lexie communes with Abe's ghost and sobs in his arms.
Getting no answer at Lucas' door, Kate frantically pictured him inside, a victim of the Killer. Arriving home, Lucas learned from his mother about Marlena. Worried about Sami, Lucas called Grandpa Shawn advising him to close the Pub and stay behind locked doors with Will. Realizing her son's love for Sami, Kate phoned Will after Lucas went out in search of Sami.
At the Horton household, Alice was cornered in a pantry. Courageously, she told Marlena, "Surely, you must know that you will never get away with this." Laughing, Marlena replied, "That's what they all said -- every single person you are about to join...in Eternity." Seated before a plate of her own doughnuts, Alice grew nervous as Marlena stroked her arms, refusing Marlena's sarcastically ominous offer. "How 'bout some nice cold milk to go with those doughnuts? I'm not completely heartless...I do think that the condemned has a right to enjoy their last meal...or snack as the case may be. And your homemade deep fried donuts are perfect."
Alice continued when Marlena said she had no choice. "Marlena, dear, you don't want to do this...you have a choice, you still have brain don't you...Think of all the happy times we shared right here in this house. You've been like a part of the family...another daughter to me and my dear Tommy. He thought so much of you." Agreeing Marlena called herself, "practically perfect in every way. Good friend, loving wife, great mother...and so much more." Alice reasoned with her. "No, you're just very sick, that's all. But we still love you."
Pensively changing moods, Marlena asked, "How can you? How can you love me after the awful things that I've done?" Alice replied, "Because we know that this isn't you. You know it, and we know it, too. So, just stop. Stop all the madness. Let us help you...now before it's too late." But leaving Alice's, Marlena stood outside the door thinking, "My dear sweet Alice. What an amazing person. Cup of tea, some words of wisdom and a promise of hope...even in the darkest of times." Licking some sugar from her thumb she added, "And the most delicious doughnuts. They really are to die for."
At the accident scene, Sami threatened John at gunpoint finally firing at him. But wishful thinking became just a fantasy as John bounded back and overtook Sami. As Sami fought him, John emphatically told her, "I am not the murderer. It is your mother." As she cried that John was lying, he could only hold Sami, in sympathy with her pain. But when she wouldn't calm down, John cuffed Sami to her car's steering wheel. Expecting he was the Killer, and that she would herself be next, John assured her, "I'm not killing anybody. I'm just going to keep you safe, and I'm going to keep you alive."
Unable to start his car, and getting no answer at Alice's, John decided to take Sami's car. Fearing he would kill Marlena, Sami screamed as John fought her still cuffed to the steering wheel. "I am trying to help your mother. She's sick, Samantha. She's sick." At that moment, John saw Marlena's car drive past, away from Alice's. John called the Brady house sending Bo to Alice's. Hope had just mentioned Celeste's premonition when Bo had to tell her, "John thinks it's your Grandma...Mrs. 'H'." Unable to answer her cell phone as Lucas called, Sami screamed when John left the scene with his revolver. Lucas and Kate found Sami moments later, disbelieving Sami's story that John was the Stalker, now headed to kill Marlena.
In her car Marlena plotted her next attacks. Planning to deal with Shawn, then John, then "all the people who know I've been a very bad girl." Tasting one of Alice's doughnuts she'd brought with her she cried, "Oh, my gosh, these are fabulous! I should have gotten the recipe." Shawn found Belle at the Loft sleeping but safe in the tub. Belle had the feeling someone was there earlier, while Shawn sensed someone outside, as Jan and Nicole stood on the fire escape. Furious that Shawn discussed Marlena with Tek, Belle was shocked that her father, John, believed the suspicions, too.
Leaving the Loft with Nicole, Jan bumped into Marlena. Marlena was quick to ask why Jan was there with Nicole, leading Jan calling her the Serial Killer. Denying it, Marlena said, "If I were, I'd have a bone to pick with you, Nicole, over Victor's death." As Nicole argued her innocence, Marlena explained the impossibility of Victor dying at the Killer's hand, deducing Jan's possible guilt. Distracted by police sirens, Marlena warned the two to keep their theories to themselves, "if you know what's good for you."
John found a relaxed Marlena at the Penthouse, in her robe. "It's over, Doc. I know. I know that you were at Alice Horton's. Did you do it? Did you kill her?" And at Alice's, Bo and Hope followed a trail of powder to the kitchen. Entering the kitchen, a shocked Hope buried her heard in Bo's shoulder from what she saw.
Lucas gets grim news from Tek about Alice. Sami and Lucas race over to the Horton house. Bo and Hope arrive at the Horton house and find Alice sitting on a chair, peaceful, her eyes closed and surrounded by donuts. Hope is beside herself; Bo finds a weak pulse. Alice opens her eyes briefly but is unable to name the killer. By the time Lexie arrives, Alice has succumbed. Bo and Hope mourn the passing of the original Horton matriarch. Alice is at peace as she joyfully reunites with the great love of her life, Tom. Sami and Lucas arrive - Lucas mourns Alice.
Sami rails at Lucas for dragging her back to his apartment - she has to save her mother from John. Sami fears John will kill her and Lucas tries to reason with her. Celeste predicts another Horton would die tonight so Lucas calls the Horton house to check on his relatives.
Shawn defends Marlena; still believing the alibi Belle gave her. Bo and Hope are painfully aware Belle is lying about her alibi for Marlena. Hope fears that when Shawn finds out that Belle's lie made it possible for Alice to be killed, it will end their relationship forever.
Belle and Sami can't believe their mother could be guilty. Belle tells Sami she can't go on lying to Shawn. Sami warns Belle not to make things worse for their mother; they know she's innocent. She warns Belle to keep lying to Shawn. When Tek finds boot prints, Sami is enraged that the cops suspect her mother of being the serial killer. No one will listen to her warnings that John is a threat to Marlena's life! Sami races out to find her mother; when Lucas realizes she's gone, he gets a very bad feeling and rushes after her.
Brady finds the burned model of the opera house. He confronts Nicole and she has to cover. Brady has lost all trust in her and suspects Nicole has an accomplice with whom she conspired to kill Victor. Jan calls and Nicole must again cover. After Brady moves out, Nicole reminds Jan that Marlena can incriminate them. Nicole urges Jan to get out of town. Nicole tries to make a run for it but Brady catches her. Where does she think she's going? In counterpoint, Jan realizes without Shawn she'd have nothing to live for and she decides to kill herself!
John confronts Marlena... now convinced she's the serial killer. Clever Marlena tries to cover but John has heard the truth from Alice Horton. Marlena begs him to give her a chance to prove her innocence. John's great love for Doc makes him give in so he covers when Bo calls ... he needs more time. Marlena tries to talk her way out of it but John finds evidence in her gloves that she killed Alice. Marlena finally confesses. In tears, she falls into John's arms and then tries to get his gun. She refuses to let him arrest her and plans to send him off the terrace balcony. There is a struggle and it is Marlena who falls off the penthouse terrace. Sami, on the street below, sees John fighting with Marlena. Sami screams as Marlena's body hurtles toward her.
Lucas arrived outside the Penthouse, as Marlena fell from the terrace. Pushing Sami out of the way, Lucas screamed as Marlena bounced off an awning and landed on Sami anyway. Beneath Marlena, Sami slowly regained consciousness herself as a hysterical Lucas sought help. Weeping, Sami touched her unconscious mother trying to wake her and saying, "I know you're innocent, Mommy." But as John made his way down to them Sami said, ."..you've killed her Are you happy now?"
Hearing about the accident, Philip joined the Brady's, Lucas, Belle and Lexie at the scene. While Sami continued accusing John of the killings and Marlena's fall, John told Bo and Hope about Marlena's confession. Hope was stunned as he explained the powdered sugar in Marlena's glove. "She's the monster" was Bo's reaction, as John suggested Marlena suffered a breakdown. But Bo angrily said, "She's not getting away with this on some kind of insanity plea." Recalling Caroline, Roman and Victor's deaths, Bo said ."..she killed them all, and she's going to pay! ... I'm sending her to death row where she belongs." Appealing to Bo as a father John asked for time to tell his daughter.
Hope found it inconceivable that Marlena could be the Killer. As she wondered how the news would affect Belle, Bo was confident that his son would never forgive the girl who gave an alibi for a murderer.
At the Kiriakis Mansion, Brady was on to Nicole's sudden change of heart as she rushed to leave Salem without a suitcase. As she suggested starting a new life and would leave Victor's Estate to Bo, Brady and Philip, Brady suggested she was guilty of Victor's death. Nicole wept saying she had opened her heart to Brady, while he admitted loving Chloe. While Brady tried to convince her to stay, Nicole changed her mind when Philip brought the news about Marlena. Believing a dead Marlena wouldn't incriminate her for Victor's death, Nicole thought she had won. But remembering the evidence Jan still had Nicole called Jan.
About to commit suicide, Jan fantasized Shawn talking her out of it and giving up Belle. But realizing it would never happen if Shawn knew about Victor's murder, Jan put the noose around her neck. As the phone rang, she debated whether or not to answer. Thinking it could be the Police Jan hung herself. But when the attempt was unsuccessful, Jan answered the phone, learning about Marlena from Nicole.
At University Hospital, John was distraught as Sami called him a murderer and Belle refused to believe him. Telling Belle that Marlena confessed, John wept urging that they show compassion for her illness. Before attending to Marlena, Lexie asked John, "Did Marlena kill Abe?" Reluctantly, he finally said, "Yeah, she's the one." Cursing Marlena, Lexie refused to treat her. As John reminded her she was a doctor, Lexie replied, "I am also a wife who would have been celebrating her wedding anniversary today." But recalling her Hippocratic Oath Lexie agreed, ."..I'm here to save lives even the life of the woman who killed my husband." A vengeful Bo surprised Hope saying, "If I was Marlena's doctor, I'd put her out of her misery."
Conflicted, Shawn convinced himself that Belle would not lie to him, while Philip consoled her. Expressing his confidence in her and Marlena, Shawn hugged Belle who was realizing the damage she had done. Watching them, Philip thought, "If Shawn lets you down, I'll be there for you, Belle." Brady was unable to believe the news. Recalling that Marlena was with John during Victor's murder, Brady left to confirm his own suspicions. Sami prepared to be discharged, asking if Marlena would live. Lexie somberly replied, "I'm sorry."
Alice was already being memorialized at University Hospital by photo flanked by flowers. Stopping by, Hope told Bo that if Marlena was guilty, the nightmare still wasn't over. Concerned about Belle, Shawn spoke to his grandmother saying, "You would know exactly what to do for her, Gram." A moment's contemplation seemed to bring Alice's answer to a grateful Shawn. "Thank you. That's exactly what she needs."
Marlena's condition was stable and expected to recover because of landing on the awning. Bo was eager to read Marlena her rights and get her behind bars as soon as she regained consciousness. Sami now cried conspiracy as she accused Kate and John of being lovers and setting Marlena up. Angry with Lucas taking Sami's part, Kate referred to his saving Sami earlier saying, "You should have let the little bitch die." Worried about Philip, Kate encouraged him to find a nicer girl than Sami. After Belle had confided in Philip about her lie, Kate suggested Philip take advantage of any rift between Belle and Shawn.
Lexie spoke to an unconscious Marlena about the many lives she took. Overhearing, Sami asked to change doctors, still declaring her mother's innocence and thinking Lexie was out for revenge. Saying, "I'm going to be ready" when her mother awoke, Sami looked out at John and Bo, adding, "I know exactly what I have to do." Bo had found John's gun with Marlena's fingerprints on it. Although this corroborated John's story, Sami said she would defend her mother.
The night before Doug's funeral, Julie and Mickey stopped by Jen's concerned about Celeste's Horton Family premonitions. Grateful that Patrick helped save Jen's baby, Julie still believed Bonnie and her son had ulterior motives. But one sight of Hope at the door caused everyone to wonder about another murder. Believing it the toughest thing she had to do, Hope shocked the family about Alice. Now, in tears herself, Hope blamed herself for not calling Alice. Julie blamed herself for going to Marlena before Doug's death. Naming Marlena as the Killer, the screams and disbelief were too much. A few moments later, Jen went into premature labor and was rushed to University Hospital.
Rex and Mimi discussed their near engagement. While Rex agreed with Bonnie that he couldn't provide for Mimi yet, he offered his heart. Arriving at the Loft, Shawn brought the news about Marlena. Asking for the woven rings that Grandpa Shawn gave Rex, Shawn announced he would propose to Belle, to give her hope. Mimi was delighted for her friend, but Rex was concerned about the possibility that Belle lied. "Shawn is in major denial. You can't start an engagement with a lie." But while Belle was trying to tell Shawn about her lie, he brought her to the Hospital roof. Getting down one knee, Shawn proposed.
And in Marlena's room, as Sami begged her mother to wake, Marlena's eyes opened. "Mom, tell them that you're innocent. Tell them that you're not the Salem Serial Killer." Catching sight of John, Marlena looked up at him and said, "I'm innocent."