Watch Castle Den of Thieves Season 2 Episode 21 Stream Online. When investigating, the team connects the dots in which might lead them to the suspect. But what about if the work is mixed with love traingle? It is a total disaster if you ask me. Anywats this will all be in the new episode of the Castle Den of Thieves Season 2 Episode 21. In this episode, Investigating the murder of a thief, Castle and Beckett are surprised to learn that Esposito has a personal connection to the suspected killer. Another surprise is in line for Castle when Beckett hits it off with the handsome Robbery detective assigned to the case, Tom Demming. The Castle Den of Thieves S02E21 broadcasts on Monday, April 19, 2010 10:00 PM-11:00 PM EST on ABC. Watch Castle Den of Thieves Season 2 Episode 21 Stream Online.