That two-way stretch,- a novel of suspense, or a suspense novel, from a writer with a long record. His new book, more original than any he has done recently, concerns Kit Hendry. Hendry, like most of Mackenzie's heroes, has had several criminal convictions; now he is given the choice of a twelve year sentence or an assignment to trace the security leakage from a Dusseldorf installation. Kit can crack safes- he can also deutsch sprechen. Under the vigilant surveillance of one Gaunt, and also of Bernadette with whom he is infatuated, he crosses the channel, is exposed to a smallpox victim, but the film he secures is the final double take in this documentary type crime story. A repeater, in the genre, but ambitiously activated.