AXE Chief, David Hawk, sends agent Nick Carter to Australia to investigate.
Carter's suspects include Lynn Delba – one of the deceased servicemen's wives; barmaid – Judy Hennicker; and Mona Star – secretary to Major Rothwell of Australian Intelligence.
In the meantime, he disguises himself as Tim Anderson – a local construction worker – and begins to frequent The Ruddy Jug.
He lets on that he is working on a nearby dam being built by a US company and is unhappy with his pay and conditions.
Soon Carter is offered a substantial sum to sabotage the dam construction – in the hope that it would further strain US-Australian cooperation.
Led immediately to the construction site to commence sabotage operations, Carter succeeds in killing several henchmen but Mona and the Chinese paymaster escape.
She also reveals that the real Mona Star was murdered en route from Britain after receiving security clearance to work for Australian Intelligence.
Carter tries to save Mona but she deliberately swims into the path of a group of sharks and is eaten alive.