One Party Can Ruin Your Whole Summer is the finale and 24th episode of Season 1 on CW teen soap 90210.
HERE YOU GO, IT IS YOU BABY – Adrianna (Jessica Lowndes) and Navid (Michael Steger) spend their prom night in the delivery room and Brenda (Shannen Doherty) shows up to offer support. Naomi (AnnaLynne McCord) and Liam (Matt Lanter) have revealed their honest feelings for each other and she decides to host an after-prom party at her new house, much to Jen's (guest star Sara Foster, "CSI") disapproval. Showing up late, Naomi searches for Liam but is speechless when she finds him finishing up some business in her bedroom.
A furious Naomi confronts and accuses Annie of sleeping with Liam, causing Annie (Shenae Grimes) to finally snap at Naomi and all the party-goers before leaving the party in a rage and doing something that will haunt her for the rest of her life. Dixon (Tristan Wilds) and Ethan (Dustin Milligan) get into a fight when Dixon accuses Ethan of having feelings for Silver (Jessica Stroup). Harry (Rob Estes) and Debbie (Lori Loughlin) chaperone the after-prom party but leave early to lend their support to Adrianna at the hospital, along with Kelly (Jennie Garth). Ryan Eggold also stars.
The episode begins with everyone still at prom and with Naomi talking to her sister Jen about Liam's past and why he behaves in that rebellious way, when Phoebe enters the room telling Naomi that the after prom party has been cancelled and they need a house so Naomi offers her but Jen does not agree.However, Naomi states that she is the one paying for everything, so will hold the party against Jen's wishes. Naomi start spreading the word about the party at her house, and defends Annie against people who believe Annie told her Dad about the original after-party. Naomi gets a text message from Navid that Adrianna is already in labour in the hospital, so she leaves her house and the party in Annie´s hands. Before leaving she says goodbye to Liam and why she needs to leave prom- Liam feels that he can trust her and he will meet her at the party, He tells her that the information he shared with her must stay between them. As everyone leaves for Naomi's party, Dixon is mad after Silver's speech, as she feels that the things he likes are stupid. Kelly gets the same message about Adrianna going into labour, and leaves for the hospital with Harry and Debbie.
At the party, Dixon is still mad at Silver and talks to Ethan, who says that Silver is special and different to the other girls they know. Dixon senses something weird about the way Ethan looks at Silver, but he thanks Ethan for the advice and goes to talk to her. Ethan stares at a picture of Silver that he has in his jacket pocket. Meanwhile Harry, Debbie and Kelly are at the hospital where Harry has brought with him some brownies from the prom and shares them with Debbie. Adrianna is in pain before giving birth whilst Navid and Naomi attempt to comfort her. Adrianna says that is to early to have her kid, but Navid tells her that the foster parents are on their way and so is Adrianna's mother. Kelly enters the room, but says that Brenda is in China and so she won´t make it for the birth, which upsets Adrianna. There is a complication as the baby's heart rate increases, so Adrianna is rushed to theemergency room to have an last minute caesarean section. After giving birth, Navid holds the baby, and asks Adrianna if she wants to see her child, but she says no, and that she wants the baby to be taken away.
Navid goes to the wating room and tells everyone that she had a beautiful baby girl. Harry and Debbie ask Navid if Annie and Dixon are at Navid's house. Navid is momentarily confused, forgetting about the after- party, but covers for Annie and Dixon, saying that they might be at his house.Debbie and Harry do not believe him, but they realize they are both acting strange. Both start laughing and wishpering and discover that they are high and they must have eaten pot brownies. Back at the party, Annie takes care of Naomi´s house and cleans up mess. She goes outside, where Liam is looking at her and she asks him what is so funny and he shows her a drawing of her as a volcano and tells her that is going to explode like a volcano soon. Later, Silver talks to Ethan about she and Dixon having doubts about their relationship beacuse they are too different and is afraid it won´t work but Ethan tells her that they can work things out and she hugs him and noticies that he is wearing Dixon jacket. Ethan gets nervous due to the picture of Silver in his jacket pocket but reaches Dixon and gets his jacket back before the picture is discovered.
In the hospital Harry and Debbie are trying to find a way to find their kids, although this is made difficult by their state. They tell Kelly that they are high, and Kelly agrees to help them. Harry asks her if she could buy them some snacks because the pot makes them hungry and after she leaves Debbie get jealous and claims that Kelly has a crush on Harry but he tells to be calm, and that the pot is making her paranoid. Meanwhile at the party, Annie finds Phoebe Abrams being sick in the toilet, and offers her help. Phoebe calls Annie "the rat", but when she tries to stand up she falls on the floor and subsequently accepts Annie´s help so she takes her to her car to give her a ride home. In the front yard, Liam is waiting for Naomi to come back, but Jen stars talking to him and introduces herself as Zelda- Naomi's neightboor. She tells Liam that his name sounds familiar and makes up a story that she overheard Naomi telling some girls about his family. This upsets Liam as he asked Naomi not to tell anyone. Jen as ¨Zelda¨ asks Liam if he is Naomi´s boyfriend, but he says he is no one boyfriend. She proposes that they should have sex, and both go upstairs.
Later Brenda appears to visit Adrianna at the hospital, but when Adrianna asks her why she isn't in China, Brenda tells her she is leaving tommorow. Brenda tell her that they are much a like, as they both love drama and both of them have a pretty dramatic life. They walk around the hospital, and while talking Adrianna notices a patient named ¨Jim Walsh¨ and asks Brenda if they are related. Brenda says Jim is her father and that he is dying. Adrianna wonders why Brenda is so calm, but Brenda says she is not ready to say goodbye to her father, and can't face it. Suddenly a dragon appears, making Adrianna confused and Brenda start talking nonsens and she disappears. Adrianna is shock, but she wakes up and realizes that it was all a dream. She stands up and goes to the nursery to cradle her baby.
Back at the party, Dixon confronts Ethan when he keeps staring at Silver but Ethan says that he doesn't feel anything for her. Dixon asks him whyhe has a picture of her in his pocket, and Ethan tells Dixon the truth, however, Silver overhears, leaving her confused. In the hospital Naomi needs to leave to check on her house, when Ty enters and gives Navid the signed forms for the adoption of the baby. He congratulates Navid and gives him a cigarette for being the father and taking the responsability and thanks him. Meanwhile Harry is passed out at the couch and Debbie takes the chance and confronts Kelly about Kelly's crush, however apologizes as she realises the pot has made her believe things.
When Naomi gets home she looks for Liam, a girl tells her that he might be upstairs. Naomi goes to find him half naked in her bed after sleeping with someone and they break up. Before leaving, Naomi picks up the wrap that belongs to Annie. After she leaves Jen walks in again complaining about her sister Naomi, making Liam find out that Jen used him to get revenge on Naomi. While walking down the stairs Naomi sees Annie coming and accuses her of sleeping with Liam. Annie says she was with Phoebe but Naomi doesn't believe her due to Phoebe's dislike of Annie. Naomi starts screaming at Annie and reminds her of when she stole Ethan and now Liam. Everyone at the party start verbally abusing Annie and calls her a ¨Kansas skank¨. Naomi kicks her out of her house, leaving Annie crying ouside the house after snapping at Naomi and the partygoers. She takes a bottle of vodka with her, and calls the police to report underage drinking at the house.
Brenda shows up hospital but Adrianna thinks she still dreaming however, Brenda says she is real. Navid interrupts them because the foster parents are in the hospital to take the baby. Adrianna begins to cry and says she didn´t wanted to see the child as she was unable to say goodbye to her but Brenda encorages her decision by telling her that she was in China adopting a baby girl and that her baby will make that couple very happy. Silver runs after Ethan, questioning what just happened, and the two kiss. Ethan then says that he does not want to be just friends, he wants to be more or nothing, then posing the question "Why are you out here talking to me? Instead of inside talking to your boyfriend?",Naomi is seen sobbing into the arms of her "comforting sister" when the police arrive at the house.
Adrianna gives the baby to the couple in tears while Navid and Brenda support her. The couple thank Adrianna and she askswhat the baby's name will be. They say they will call her Maisy. They leave the hospital and Adrianna breaks down crying. Liam calls Naomi but she does not pick up so he leaves her a voice mail but it´s interrupted by Liam's stepdad and two of his well built friends hurling Liam out of bed and dragging him out of his room while he shouts for his mom. At the end, Annie is seen driving her car upset and looking at a bottle of alcohol. When suddenly she crashes into someone, a car is then seen driving around the corner and Annie dives off. The car stops at the body and the identity is not revealed. The car also had a WBHS (West Beverly High School) bumper sticker on the back, suggesting its driver goes to school with Annie.
- Rob Estes as Harry Wilson
- Shenae Grimes as Annie Wilson
- Tristan Wilds as Dixon Wilson
- Dustin Milligan as Ethan Ward
- AnnaLynne McCord as Naomi Clark
- Jessica Stroup as Erin Silver
- Michael Steger as Navid Shirazi
- Lori Loughlin as Debbie Wilson
- Jessica Lowndes as Adrianna Tate-Duncan
Special Guest Stars
- Lily Collins as Phoebe Abrams
- Mickey Meyer as Duncan
- Meaghan Tandy as Savanna
- Wendy Norton as Penelope
- David Chisum as Greg Davis
- Maureen Flannigan as Leslie Davis
- (after Adrianna gives her baby away)
- Adrianna: (cries) I did the right thing, right?
- Brenda: You did a really good thing (hugs Adrianna)
- Silver: Ethan, Ethan! Where have you been? What's going on? What was that?
- Ethan: I never wanted to say anything
- Silver: I don't know what to do with this, okay? I mean, you're one of my best friends, but that's it, right? We were just friends
- (Ethan kisses Silver)
- Ethan: I don't think we're just friends
- Silver: Ethan, no
- Ethan: I don't wanna be just friends. I don't think I could take it
Opening Tagline: Annie
- Last appearances of Ethan Ward and Brenda Walsh
- Brenda reveals she adopted a baby in China
- Jim Walsh is mentioned for the first and only time in the spin-off.
- The title is said by Harry Wilson in Zero Tolerance.
- At the very end of the episode, Annie kills a man. The man is revealed to be Jasper's uncle, and his body is found in the second season, by Teddy.
- "The Only One" by Manchester Orchestra
- "Panic" by The Boat People
- "Beautiful People" by (uncredited)
- "Bang Bang" by K'Naan
- "Waking Up In Vegas" by Katy Perry
- "Everyone's At It" by Lily Allen
- "Superthug" by Noreaga
- "Absolute" by The Fray
- "Sugar" by Flo Rida featuring Wynter
- "Back Again" by Parachute
- "Let Go" by Amy Bell featuring Genise
- "The Funeral" by Band of Horses