The Executioners is a novel in the Killmaster series of spy novels, published in 1971.
The Australian armed forces have been messing up badly. One of their carriers rams and destroys an American cruiser. A pilot accidentally drops live bombs during war games. An out-of-control tank sets off an explosion that decimates a British army contingent. Nick Carter is sent to investigate, working alongside Major Rothwell and his assistant, Mona Star. After a few near misses with death, and the deaths of the men who were at the hearts of the accidents, Nick uncovers a Chinese plot to drive off Australia’s allies, an underwater base on the Great Barrier Reef, and the shocking secret that the plot is not truly Chinese, but the brainchild of a bitter woman whose father was ruined by the Australian army – and who killed and took the place of the real Mona Star, years ago. The plot is ended by a couple of navy torpedoes and a school of sharks.