Lee Van Cleef plays a fiercely independent river ferryman in the Old West. Bandit Warren Oates, fresh from decimating a local town, rides up with his gang and demands that Van Cleef transport the crooks and their booty across the river. He refuses, and is taken prisoner. Biding his time, Van Cleef is able to turn the tables on the vicious gang.
Heavily influenced by the ultraviolent spaghetti western school, Barquero attempts to add a contemporary note to the proceedings by having Warren Oates take an hallucinatory trip after smoking an unidentified weed.