"Retired policemen Grijpstra and de Gier are being blackmailed. The threat is a serious one: to set the income tax authority on them. The blackmailers, a wealthy yacht owner and his son, want them to investigate the mysterious hijacking of a supertanker's entire cargo in the Caribbean. The Amsterdam cops reluctantly agree to take the case. Their rendezvous is in Key West, where they are confronted with a murder."--Back cover.