Moonfleet

Moonfleet is a tale of smuggling by the writer J. Meade Falkner, first published in 1898.

Warning: wikipedia contains spoilers

The novel is set in Dorset during the late 18th century. The story concerns a boy who becomes friends with an older man who turns out to be the leader of a gang of smugglers.

The book was filmed by Fritz Lang in 1955, with a screenplay adapted by Jan Lustig from the novel, and starred Stewart Granger.