After a shadowy assassin ambushes his prison transport van and guns down a convict, humiliated penitentiary guard Daijiro (Michitaro Mizushima) stubbornly risks his own life to capture the mysterious mastermind responsible for this and several other brutal murders. Directed by Seijun Suzuki, this thrilling Japanese whodunit also stars Mari Shiraki, Misako Watanabe, Shinsuke Ashida and Shoichi Ozawa.