Michael agrees to help a client rescue his kidnapped sister, but Michael gets more than he bargained for when he realizes the entire case was a ruse set up by an old enemy, Natalie (Ep. 308). Natalie tells Michael she was doing business with some South American revolutionaries and discovered they were in possession of a chemical weapon. Natalie may be a thief, but she isn't a mass murderer. She wants Michael's help to get the weapon away from the dangerous revolutionaries before they can use it to kill innocent people.
Michael and the team must also track down Justin Walsh, the man in possession of the list that can take down Vaughn and his organization. Michael learns that Walsh is planning on auctioning the list to the highest bidder, and the only way to stop Walsh is for Michael to get in on the auction himself.