Kate Wilson, fortyish and tied down to a demanding hypochondriac of a mother, lives for her occasional weekends at a nearby resort hotel--where she blossoms into a chic sophisticate and carries on a gentle affair with her boss, a married doctor. One weekend, however, she stops along the way to help a stranded woman motorist, moving on when a personable, helpful fellow happens by; and when the personable, helpful fellow carelessly murders the motorist, during an attempted rape a few hours later, he knows that he must track Kate down and murder her too. Yorke, author of the attractive but little-known Dr. Grant detective series, does a sure, economical job of setting up this not unfamiliar situation. But better still is her handling of characters: the killer is no maniac, but rather a self-deluding, childish fool; and Kate, in the crisis, turns out to be no twittery damsel in distress, but rather a quietly tough customer who, though wounded and terrorized, snares the villain with a hard-won panache reminiscent of Dick Francis. Unspectacular, but neat and sharp.