The investigation gets personal for Detective Esposito in Den of Thieves
as it involves the Mafia boss who killed his old partner, Ike Thornton. As it turns out, Esposito's former partner isn't really dead. He's been living off the radar ever since he was set up as being a dirty cop. The team manages to catch a killer and clear Thornton's name. There's a really cool moment when past and present partners meet for the first time. Esposito says, "Ike, this is my partner Ryan. And this is my other partner Castle." Nice.