Stuart Northcote, a London adventurer, slays the president of a mythical South American republic, and establishes himself at its head. Mercia Solano, daughter of the slain official, leads a conspiracy to avenge her father's death by killing Northcote. The adventurer escapes to London, however, after looting the republic's treasure chest. He is pursued by Mercia and a band. The adventurer, perceiving his deadly peril, employs Jack Burton, an impoverished young Englishman, to act as his double. The girl shoots at the double, and other fiendish plots are carried out to kill him. Burton frustrates them all.