Upset to see Lucas has special plans for tonight with Carrie, Sami accuses him of doing all he can to get her into his bed but he insists he cares for her. Sami boasts that she will win Austin. As she leaves, Austin runs into Carrie and asks her if she's like to get together with him later. Austin approaches Caroline and asks her to put together a picnic featuring all of Carrie's favorite foods. Lucas then arrives at the Pub and asks Caroline for Carrie's favorite dessert for his special evening at his place. Though they fail to see each other at the Pub, they run into each other at home where Lucas boasts he has a "hot date" with Carrie tonight. Meanwhile, Carrie seeks advice from Lexie who was kissed by Tek again. As they talk, Sami spots them and hides nearby so she can listen to Lexie tell Carrie not to worry about Sami. She also urges her to pick the man she wants to have a family with. Sami's upset when Lexie gets Carrie to confess that she loves Austin more than Lucas. Lexie urges her to be honest with Lucas before it's too late. After Carrie leaves, Tek rushes to Lexie and starts ripping her clothes off as they kiss. Sami is outraged but considers how she can use this. She later spots Carrie on the ground in pain. At church Bo asks Shawn to postpone the wedding until Hope returns. Mimi hears them arguing and convinces Shawn to forgive Bo who is thrilled to be invited to the wedding. Pushed by Father Jansen, Mimi fails to tell Shawn about Claire. With Patrick's help, Hope saves the little boy as they both tumbled over the edge of the cliff. Patrick finally pulls Hope up but she admits she can't feel her legs. He tries to call Bo but when he hands the phone to Hope, she hangs up just after Bo answers. Patrick takes Hope back to their shelter where he promises he'll always be there for her.
Alex brings Lexie for a visit with Marlena and she advises Marlena she's there on John's behalf. Secretly listening, Alex interrupts and tries to put Lexie down, reminding Marlena that Lexie declared 12 people dead when in fact they were still alive. Lexie counters that she recommended Alex to John. Looking at Marlena's bottle of sleeping pills, Lexie asks Alex to leave so she can examine her but he won't allow it. After he forces her to get out, Alex shows Marlena a brochure for a place he intends to take her for their honeymoon. Alex then slips away to Lois' cabin and after searching for any photos, he decides to destroy the place. Meanwhile, at the Pub John tells Abe and Tek he thinks Alex is drugging Marlena. Lexie joins them and explains she doesn't think Marlena's on anything other than a weak sedative so Abe warns John to stay away from Marlena. When John decides to do more snooping into Lois' past, Abe offers to help him leaving Lexie with Tek. He admits how much he liked their time together in the park and though she claims it can't happen again, she agrees to meet him later. John and Abe run into Alex as he leaves the cabin. Sami fails to help her sister as she cries out in pain but once the cramp disappears, Carrie's okay. She hears Sami sneeze and Sami lies that she just happened to walk by. Sami pushes her to be with Lucas so she can have Austin. They return to the restaurant where they interrupt Lucas and Austin arguing. In the church Father Jansen is fooled into thinking Mimi told Shawn about Claire and agrees to marry them. Shawn then surprises her with a special private party at the park with Philip and Belle there too. As he dances with Belle, he tells her he loves Mimi and is marrying her tomorrow. He warns if she can't accept this, he doesn't want her at the wedding.
Tek brings Lexie to a new nightclub called Dune but she becomes upset when she finds Sami, Lucas and the others hanging out there. She insists that she will not end her marriage for him. As they dance, Austin asks Carrie for another chance but suddenly, Carrie feels another pain and collapses into Austin's arms. Eugenia yells at Lucas for being with Sami again but he insists he's with Carrie. Bo stops by to see Billie and Chelsea to try to calm things but he and Billie realize that Chelsea is missing. Meanwhile, also at the Dune Chelsea is falling prey to a thug who doctors her drink and then invites her to come with him to his place. Max tries to come to her rescue but she doesn't want to listen to him so he lets her go. Max then calls Bo and warns him about the trouble Chelsea's facing. Caught outside Lois' cabin, Alex encourages John and Abe to search the place themselves as he proclaims his innocence. None are aware that Marlena is there to retrieve clothes for Lois to wear as she's buried. As she does so, the cabin blows up. Deciding to spend the night apart, Mimi ends up sleeping with Belle while Shawn is with Philip. Mimi is startled when she hears Belle talking in her sleep that she intends to stop Shawn and Mimi's wedding. Worried, she grabs the phone and places a call. Helping Hope cope with her sprained back, Patrick urges her to realize she must go back to work things out with Bo.
Belle manages to wake Shawn and asks him to meet her up on the roof for a chat, unaware there are already two people up there. As they arrive, Kate and Mimi hide and listen. Belle tells Shawn he is making a horrible mistake marrying Mimi but he refuses to cancel the wedding. Belle warns that she will not allow him to marry Mimi as Kate and Mimi react silently. Later, Mimi assures Kate she knows what she must do. Bo and Billie stop by Club Dune to look for Chelsea. Inside, Derrick pushes Chelsea to finish her spiked drink and when she refuses, he tries to force her hand. Just then, Bo comes up behind him and starts fighting, eventually admitting he's a cop and Chelsea's father. Derrick runs off after grabbing his PDA. Bo takes Chelsea outside and lectures her about her antics. Once they're at home, Chelsea admits she's feels like she's been drugged. Bo reveals he took the memory stick from the PDA and shows Billie and Chelsea photos of numerous young women Derrick took home and assaulted. While Chelsea goes up to bed, Bo and Billie argue about turning Derrick in because he could help ruin Chelsea's hopes to stay out of prison. Bo eventually deletes the photos he took of Chelsea. Seeing Lexie emerging from a back room at Club Dune, Austin asks her for help with Carrie. Lexie orders her to the hospital for treatment. At the hospital Sami's upset to find Lucas and Austin worrying about her sister who is diagnosed with acute appendicitis. After the surgery, a nurse assures them Carrie will be fine. At the cabin John plays the hero and rescues Marlena from the burning room, telling the paramedics that he thinks this was arson. When Alex arrives at the hospital, John blames him for the explosion but Alex thinks Lois set the trap long ago. Sami arrives and starts blaming John until Abe quiets her. Lexie emerges with some bad news.
When Carrie wakes, Sami is there to greet her but then admits her concern about Marlena. Lexie assures John, Alex and Abe that Marlena's injuries are not life-threatening. John and Abe insist Alex come with them to the remains of the cabin. Lexie advises Carrie that during her surgery, they found the scar from her ovarian cyst rupture and urges her to have children soon for fear she may become infertile. Sami overhears Lexie urging her not to worry about Sami when she picks the guy she wants to father her children. As the Brady Pub celebrates St. Patrick's day, Belle has too much green beer and boasts to Caroline that she is going to stop Shawn and Mimi's wedding tomorrow. Caroline reminds her of her own vows to Philip and suggests that Philip may want to sue for sole custody of Claire if she does this. Belle asks her about her situation with Victor, knowing that Bo was his son. Caroline explains that Belle and Shawn don't share a child which is a big difference. She urges her to let him go if she truly loves Shawn. Victor interrupts and asks if she would still choose Shawn if she had the choice. Caroline claims she would make the same decision. Shawn finds Bo stewing outside the Pub, unwilling to join the festivities inside. After telling his father he doesn't want Chelsea in their family, Shawn leaks that Belle's been trying to stop him from marrying Mimi. Bo suggests he take some time if he's having doubts about marrying Mimi. Shawn insists he's marrying Mimi. At the cabin, the investigator announces that a faulty water heater caused the explosion though a wrench was found near what's left of the appliance. John threatens Alex who announces he's going back to Marlena. John then tells Abe he'll kill Alex to protect Marlena.