Appealing intrigue -- light on violence; Cloak of Darkness, by Helen MacInnes. New York: Harcourt Brace Jovanovich. 352 pp. $13.95

In this, her 20th novel of suspense and intrigue, Helen MacInnes once again proves that spy stories don't have to be vicious or perverse to hold readers' attention. Strong characters and intricate plots are what we want.

The hero this time is an American who's recently set up an international counterterrorist organization. A rarity among espionage agents, he is devoted to his wife, abhors killing, and is repelled by torture. Instead, he has the kind of quick mind and intuitive sense of approaching danger that turns each twist of the plot into a palpable cliffhanger.

As the action moves from London to New York, Washington, Paris, Chamonix, Amsterdam, and exotic Djibouti, the author sneaks in ever more fascinating glimpses of modern intelligence agencies at work. Although there's a feeling from the beginning that the good guys will win, how they'll do it against a backdrop of very timely settings makes for a more than satisfying conclusion.