Ahmed's in critical condition, and Linden and Holder are essentially starting from scratch when we pick up. They sift through the evidence and Linden's careful to show viewers a key with an unusual chain that looks like a bird within a gold circle. They put calls out to local cab companies to find out if anyone picked Rosie up from Ahmed's after she dropped her books off that night. Holder lectures Linden about never leaving the office, so she does ... but she doesn't go home to Jack quite yet. First, she pays a visit to Richmond, to let him know that Ahmed is no longer a suspect, but he is in critical condition. They share a drink, but very few words other than for her to admit she was wrong. Oh, and in this show's typically subtle fashion, we find out Richmond made the shot because we see him set down a basketball on his way to answer the door when she arrives.
This Ahmed news is, of course, bad for the case but good for the campaign. Also bad for the Larsens, though, especially when Stan turns himself in. Linden and Holder decide it's time to look into his Polish mob ties, so she questions him in jail (though it doesn't amount to much other than her telling him she heard his 9-1-1 call about Ahmed, which seems to redeem him some in her eyes) while Holder questions a very fishy-acting Belko. He keeps his hand in his pocket the entire time, which we know is because he was part of the Ahmed beating. Soon, Linden and Holder find the cabbie who picked Rosie up. He checks his ledger and says he dropped her off at home. Then he gives them his security camera. They watch her arrive, and Holder notices a light in their house is on until she gets out of their car, when it goes off. Since the Larsens were out of town that weekend, it's pretty spooky. Linden questions Terry, who thinks Belko's a weirdo who has a key; Holder goes back to Belko, who is a weirdo who has a key. He was with his mom that night, though, he says. And his gross sexpot mom (who's 70) confirms this. But when they see his room, they notice pictures of the Larsen family all over the ceiling above his bed. Too creepy to be true, right?
They question Belko, and Linden's the one who's a hard-ass on him this time, until she softens and gets him to spill that he was in the house when she came home, but he hid because Mitch hates it when he goes in the house. He says he heard her in her room, and then on the phone to someone named "Adela." Which rings true to Linden, since she found the "Adela, Friday11:45" note in Rosie's textbook.
Meanwhile, someone sorting footage for Richmond's new campaign ads -- now that Ahmed's innocent, he's focusing on that and on cutting budgets for each city council member (not worried about burning bridges now that he looks like the good guy -- finds a shot of him shaking hands with Rosie Larsen. She shows Gwen and Jamie, who take the disc and ask campaign aide Valerie not to tell anyone else. She says she won't, then Jamie and Gwen decide not to even tell Richmond. He needs plausible deniability and needs to believe he's never met her (unless he has). In the end, Gwen stares at the paused shot of Rosie and Richmond shaking hands, Mitch finds out their entire $16,000 savings has been cleaned out but Stan's not around to ask about it, and Linden takes the Adela ferry to a casino that has the same symbol as the keychain in evidence. We must be getting close, right?
Previously on musical suspects: Richmond took a $5 million shot. Mitch ID'd the pink Grand Canyon T-shirt as Rosie's, then found Rosie's in the laundry. The key found on Rosie didn't fit her locker, so Holder suspected she had a secret lockbox somewhere. Linden found a note in Rosie's Quran that said, "Adela, Friday 11:45." Mitch guilted Stan into beating the crap out of Ahmed.
We open on a shot of broken glasses and a broken body lying in the rain. We pan up to the face to see it's Ahmed, looking as good as dead. Abrupt cut to Mitch leaving Stan yet another message urging him to call her back. He shows up then, and she says she's been calling and calling. Then she sees the blood all over his hands and even on his face. She shows him the pink Grand Canyon shirt she found in the laundry, meaning the shirt Ahmed has wasn't hers. Mitch is clearly regretting going Lady Macbeth on Stan.
SPD. Linden and Holder fill their boss in on the latest development: Muhammed and Ahmed are innocent of murder (though they kidnapped a girl, that's not really the business of this homicide team). Their boss says that's too bad since Ahmed's in critical condition after someone beat him half to death. Holder looks at Linden, who puts her face in her hands. Credits.
Stan watches Denny and Tommy sleep, as Mitch stands in the doorway watching him. He walks toward her, then right by her without speaking.
SPD. Holder looks defeated and gets up to leave, but Linden's not ready to do that. She starts throwing things around, and says she never should have talked to the Larsens about Ahmed. Holder says it's not her fault; he was a good suspect, since he lied to them several times and seemed shady. If he'd been straight, things would have been different. Linden points out that "different" in this case could mean he'd be in jail for kidnapping a minor. Holder says he feels bad about it, too, but he's not going to let himself lose sleep over it and Linden shouldn't either. He asks if she's coming. She says she is, and gets up to leave. But first she gets a call telling her that Stan Larsen turned himself in.
Stan gets patted down and felt up by a guy wearing blue rubber gloves. They fingerprint him, take his mug shot, and he changes into an orange jumpsuit. Then they shackle his feet like he's a hardened criminal and lead him to jail. Lights out. Man, that's depressing. Although, is it really any more depressing than the life he's been leading with Mitch?