The Cat Cracker

Published in the UK magazine Argosy, 05/1962. Also published as The Catalytic Agent in 3 issues of Ellery Queen's Mystery Magazine (US - May 1963, UK - Sep 1963 & AUS - Nov 1963). Printed in the collection Game Without Rules.
Behrens runs into a former student, Alan Tabor, from when Behrens taught Latin. They share a meal and discuss life in general and science in particular. Tabor is pondering leaving England, possibly working for the other side. Behrens is keen on convincing him to stay and, it turns out, has a sort of secret weapon.