River Patrol is a 1948 British second feature ('B') crime film directed by Ben R. Hart and starring John Blythe, Lorna Dean, and Wally Patch. The screenplay was likely written by the film's editor James Corbett, but there is no writer's credit listed. The film concerns a group of undercover British customs officers who investigate a gang of smugglers. It was made by Hammer Film Productions at Marylebone Studios in London. It is notable for being one of the earliest films made by Hammer following its relaunch after the Second World War. Its running time was so short, many reviewers considered it more of a short subject rather than a feature film. Nevertheless, it is today considered a lost film

Plot

Two British customs officers, Robby and Jean, go undercover, pretending to be husband and wife in order to smash a ring of smugglers along the Thames. During the investigation they visit the most shady places of London, including "Sure", a night club with the worst imaginable reputation in the city. The fake spouses befriend and dupe the night club owner and find evidence leading to the identity of the top boss of the smuggling ring. The criminals are planning to smuggle 20,000 pairs of nylon stockings hidden in laundry baskets. However, the agents' identities are discovered by the criminals before they can report back to their superiors, and they are kidnapped by the thugs and held prisoner until they are rescued by the River Patrol.