Volume four begins with Amos finding that Carrington had invented the Tanner identity and suspecting him of being part of the conspiracy to kill the President. XIII, under the name of Ross Tanner, has been hidden by Carrington in a SPADS training facility in the fictitious Latin American country of San Miguel. Amos continues to delve into the files and learns that Steve Rowland was murdered shortly after the assassination. Amos now assumes that Rowland was the real assassin, and is confused about XIII's real role, but he exposes Judge Allenby, the head of the investigation, as one of the conspirators. Amos interrogates Allenby, who is killed by Mongoose's assassin; Amos himself is rescued by Kim Rowland. Meanwhile, a female SPADS Sergeant named Betty Barnowsky reveals to XIII that she saw Steve Rowland in Eastown after his alleged death, in company with SPADS Colonel Seymour McCall. XIII, Barnowsky, and Jones escape an assassination attempt by McCall but end up lost in the San Miguel jungle.