The supporting characters on Castle are used almost primarily for comedic relief to the point where Ryan and Esposito are mere pastiches sometimes. "Den of Thieves" revolved around Esposito past at the 54th Precinct. After a thief is found tortured to death, fingerprints on his eyes belong to Ike Thorton, Esposito's former and purportedly dead partner. There were many great moments and the episode ended happily with the crime boss, Racine, getting arrested, validating Thorton's quest.
Detective Tom Demming is brought in the help and immediately clicks with Beckett to Castle's dismay. He loses to Alexis at poker and after showing displeasure, tells her that he doesn't like to lose. The bigger issue is that he doesn't like to lose to Demming. The season finale is in two weeks, so Demming could show up again to perpetuate the love triangle.
Score: 9.0/10
