Castle (2009)

S4E2 Heroes & Villains

After an ex-con is found dead in an alley under suspicious circumstances, Castle and Beckett suspect a vigilante might be responsible for the crime. Their investigation hits a snag when they learn that the potential suspect dons a superhero costume and could actually possess heroic qualities. As they race against time, will they be able to apprehend and reveal the identity of this elusive figure before he claims another victim?