Julian Quist, PR-man and sometime sleuth, plays a minor but crucial role this time around. His longtime love Lydia Morton, it so happens, is among the 300 people being held hostage in the Stirrup Cup restaurant--part of a racetrack outside N. Y. City. The captors are ""The Reapters,"" a motley fanatic crew; and they're demanding the surrender of the judge and prosecutor who recently got a Reaper leader convicted of murder (the leader killed himself in jail). So Quist works frantically with old pal Lieut. Mark Kreevich--and with hostage specialist Capt. Fred Haller--to find a weak link in the Reapers' anonymous chain of command. . . before the US Army's Major Huntoon mounts what can only be a disastrous attack on the restaurant. True, the whole hostage scheme lacks plausibility. But there's plenty of suspense, Quist seems (for once) almost human, and this is one of prolific Pentecost's more diverting recent efforts.