When two vacationers are reported missing in a sailing accident at a Mediterranean island, their four friends back in London decide to investigate.

Questions begin with the fact that there were originally three vacationers—Reynard, Klara and Anton. So which two are missing? Was it a tragic drowning or something sinister?

As told by the unnamed fourth member of the investigative expedition, this is a light-hearted and amorous odyssey featuring friends Roderick, Greta, and Diane as they go in search of answers. Each has theories about what happened, drawn from past romantic attachments with the missing and fond reminiscing.

Their voyage of discovery leads to island exploration and a climactic bacchanal in an old fortress. Could jealousy be a motive in the disappearance, as Roderick suspects? Has Anton, the youthful initiate into romance, rejected the advances of his two more experienced companions? Or does the island have still more to reveal?