Castle (2009): Season 4, Episode 2

4 - 2: Heroes & Villains

When an ex-con is mysteriously slain in an alley, Castle and Beckett believe a vigilante is behind the murder. But efforts to identify their suspect are thwarted when they discover that he roams the city in a Superhero costume -- and may indeed be a Superhero. Can they capture and unmask the killer before he strikes again?.