Published in TV 21 Annual 1971, 1971.
An appeal for help from an old friend takes Simon Templar, the Saint, to a government research center in the wilds of Cornwall. He is surprised to find his frequent 'foil', Chief Inspector Teal, there as well. The trouble relates to three scientists working on a prototype of a new tank. Two of the men have disappeared and the third, Templar's friend, is worried he will be next.