The movie occasionally feels clumsy and self-defeating, yet Richard Johnson ("Wilde") does his best to maintain viewer engagement throughout its ninety-minute length. He portrays a British intelligence operative tasked with eliminating a Czech scientist who has defected and is now working for the CIA in Britain. As expected, this mission proves far from simple, growing increasingly convoluted when he uncovers a widespread network of individuals whose loyalty he questions. Among these untrustworthy figures are his superior, "Canning" (Harry Andrews), along with several familiar British actors—Gordon Jackson, Maurice Denham, and Diana Dors—as well as his CIA counterpart, "Lucinda" (Sam Wanamaker). Following the style of John Buchan's "39 Steps," the investigation takes him to a secluded Channel Island where danger awaits and casualties mount. The film feels somewhat overextended; trimming it down to around an hour would have resulted in a more captivating experience. Director Seth Holt could have benefited from reducing the lengthy introductions of characters and some of the rather verbose conversations. However, the latter part does provide a reasonable amount of suspense and functions as a passable Cold War thriller that will entertain for the moment, though it’s doubtful anyone would actively seek to rewatch it.

Source on TMDB