The Fosters - Season 3, Episode 20: Soundtracks

During Jack's memorial

At the launch party for the Fost-N-Found app. 

Mad at Mariana's betrayal, Nick uses Mat's letter to Mariana to burn down the warehouse and the sets to R&J along with it.

Callie tells Lena and Stef that the claims that Justina made about her and Brandon are true; as a devastated Nick arrives at school, he tearfully opens up the glove compartment to reveal a gun inside.

Callie contemplates her actions when Brandon arrives at her bedroom and assures her that she did the right thing, they embrace when Lena arrives; Lena tells Callie that she's proud of her.