The high school Winter Ball ended with a shocking incident on the latest episode of "The Fosters."

In "Metropolis," Callie (Maia Mitchell) has a surprise visit from an old friend, Wyatt, after she has a chat with Brandon (David Lambert) in the music room.

In class, Jesus is struggling with his work because he is no longer taking his medication.

Marianna (Cierra Ramirez) talks with Zac (Julian de la Celle) about the winter dance, but he's too shy to ask her to go to the dance with him.

Meanwhile, Ana tells Stef (Teri Polo) that her son paid her off to lie about the night her partner killed Evan, and that she will go to the district attorney to rat them out if Stef doesn't give her $10,000. Stef refuses, and tells her that she will arrest her for bribing an officer if brings that up again.

At Brandon's father's house, his dad's girlfriend tells him that if he wants Callie back, he needs to tell her his true feelings before Wyatt steps in. At the same time, Callie receives a text from Wyatt, who is seen sleeping in his car. Wyatt then gets his car towed away while he's in the bathroom.

Later, Zac finally asks Marianna to the Winter Ball.

In class, Callie finds out that she was nominated for Winter Queen as a joke from the mean kids.

Wyatt later tells Callie that he doesn't have a place to stay after his car got towed, so she connects him with her friend from the youth home, who allows Wyatt to stay at her place.

Later, at dinner, Lena (Sherri Saum) tells Callie that the principal did not give her a good report to tell her parole officer. She says that Callie is being antisocial and not speaking to the other kids. Lena and Stef tell her to go to the formal so she can prove that she is above the mean students who are getting under her skin.

At the dance, Brandon dances with Callie, while Jesus (Jake T. Austin) gets turned down from his crush.

Marianna and Zac are dancing when Zac's mom, who is chaperoning the dance, cuts in to dance with her son. While they're dancing, she accuses him of having sex with Marianna, then runs off.

Meanwhile, Callie tells Brandon that she can't be with him because they will soon be foster brother and sister. But, he is still in love with her, so he tells her to tell him something that will make it easier to get over her. Callie tells Brandon that when she and Wyatt ran away together, they also slept together.

Callie then wins the Winter Queen title, and is forced to dance with the Winter King.

The principal goes into the bathroom to find kids drinking alcohol, and they tell her that Callie gave it to them so they would vote for her. The principal accuses Callie of buying liquor with a fake i.d.

Jesus gets into a fight with his crush's boyfriend because he thinks he is going to drink and drive, but it turns out she was the designated driver all along.

At the same time, Zac and Marianna finally find Zac's mom by the water, but she doesn't recognize either of them.

Brandon then confesses to the principal that he was the one who bought the alcohol with the fake i.d. because he was trying to get back at Callie for refusing his love. A furious Stef tells the police to arrest him.

Then after he is taken away, Callie realizes that the culprit was actually Brandon's friend, who was trying to get back at him through Callie.

As he's getting into the police car, she tells him that what she said about her and Wyatt isn't true.

At the police station, Brandon tells Stef and his dad that he bought the fake i.d.s and alcohol because he needed to pay his dad back for the piano lessons, as the money for the lessons went to pay off Ana so she would change her testimony and not go to trial.

On the next episode, "Adoption Day," "Everyone is faced with their own challenges as Callie reflects on her and Jude's upcoming adoption, Mariana tries to help a friend, and Jesus plans to manage his ADHD. Stef and Mike uncover a shocking revelation, and Brandon makes another poor decision. Meanwhile, Jude gets asked on a date."

In other "Fosters" news, Nickelodeon star Ashley Argota will join the show in season two as Lou, a singer who strikes Brandon's fancy. Lou is described as a "single-minded, charismatic free spirit" according to TVLine.

Watch the promo for the spring finale below, which airs Monday, March 24 at 9 p.m. EST on ABC Family.