AllMovie

This detective thriller features one of the most exciting boat chases ever filmed, a scene that has been compared to the car chase in Bullitt. It is also notable for having much scenic footage of the Netherlands and of Amsterdam. In this film, the headquarters of a drug-smuggling cartel is the quarry of American narcotics agent Paul Sherman (Sven-Bartil Taube). Though the cartel's activities are centered in Amsterdam, Sherman's search for the headquarters leads to an island castle owned by an offbeat religious group. Sherman and his partner Maggie (Barbara Parkins) run into serious trouble when they try to gain access to the forbidding site. Paul escapes captivity and chases the culprits by boat.