Pretty Little Liars - Mona Is Interrogated About Killing Wilden - "Into the Deep" (4x09)

The episode opens with Mona being questioned by a detective. She says she killed Detective Wilden in self-defense after he grabbed her. She had no choice; he was going to kill her. The detective tries to trip her up by saying she fired the gun 3 times, but she repeats she only shot him twice. He asks her what Mona overheard Wilden say at the Halloween party, and Mona says that he was worried that Garrett was going to tell the truth about what happened the night Alison died. The detective asks why she didn't go to the police, and Mona says that she was worried that she was going to get in trouble for sneaking out of Radley, something she has done "many times." Mona tells the detective that Wilden was obsessed with trying to pin Alison's murder on the Liars. The detective asks, "So you tried to blackmail him?" Mona replies yes, but says that once he realized that she knew he killed Garrett, he became enraged and wouldn't let go, leaving her no choice but to kill him. She says she is only confessing now because her friend's mom doesn't deserve to be convicted for a murder she didn't commit. Paige throws Emily a surprise birthday party with even more surprising guests — Jenna and Shana but it's the actions of "A" at the party that lead to the biggest shock of all. Mona's selfless act provides Hanna and her mother with their first bit of good news, but it sends Mona down a familiar path. Ezra gets some distressing news from Maggie regarding her and Malcolm. Meanwhile, Aria and Jake continue trying to define their confusing relationship. Emily meets with a world-class coach in a last-ditch effort to salvage her swimming career. #PLL #PrettyLittleLiars