First, a fishing trawler runs aground on the Massachusetts shore. Then, a young scuba diver sent to investigate the wreck is found floating lifeless in the water.

Doc Adams, the unhappy friend of the unlucky aquarian, has just been launched through the stormy seas and blood-flecked sands of the Cape Cod coast to plumb the depths of a murder he should have prevented. There he uncovers a hidden treasure in illegal arms and barely survives a near-fatal confrontation with a gun. That leaves the killers he’s hunting with the comfortable feeling that Doc is dead.

Now Doc can watch for the first wrong move they make…

What starts as a pleasant summer on Cape Cod for Doc and Mary Adams turns suddenly chilling when their house guest is murdered in his bed—with the very pills that control his epilepsy. Their son Jack becomes the prime suspect. After all, the victim had been Jack’s rival both at Woods Hole Oceanographic Institute and for the attention of a beautiful whale watcher named Alice.

The evidence is too damning to ignore, but an enraged Doc knows his son is innocent and sets out to prove it. His only clue is that the real murderer must have been very interested in the victim’s top-secret lab work…