Secret service agent Martin Sheppard is ordered to go out West to investigate a plot to steal land from the Apaches. Upon his arrival, he is bushwhacked. Martin is injured during the scuffle, and he loses his memory. Discovered in his pocket is a bill of sale with the signature of "Joe Smith," the only remaining clue to his identity.
Martin soon discovers that this "Joe Smith" is wanted for murder. In a desperate attempt to discover his true identity, Martin takes a job working for Isabella Shaw, owner of the Box Slash Ranch. A tortuous trail of betrayal turns deadly when he is forced to defend the very woman who has set him up to be murdered.