Based on a story from the Heian period (794-1185), Gate of Hell opens in the midst of a revolt against Emperor Goshirakawa by the rival Minamoto clan. In order to protect the Emperor and princess Josaimon-In, decoys are sent in the form of Moritoh, a warrior of the imperial palace, and Kesa, a lady in waiting to the princess. The two escape to the deserted house of Moritoh's older brother, only to discover that he has joined the rebels. However, the insurgency is quickly quashed, and the heads of the decapitated traitors hung from the Gate of Hell at the palace entrance. Moritoh is granted any wish he desires and asks for Kesa's hand in marriage, but she is already married to Wataru, a favoured warrior of the Emperor. However, Moritoh refuses to take no for an answer ...