The Third Assassin — Howard Charles Davis

Two attempts have been made on the life of General Cortez, a ruthless South American dictator, on an incognito stay in England, when cashiered Army officer William Gatt is offered the job of the third assassin. However, whilst carrying out the plans of his mysterious sponsor, Gatt is captured by the Cortez party. Complications follow when Cortez is shot with Gatt's rifle - but who was the third assassin?