After the death of her mother, Mary Yellan crosses the windswept Cornish moors to Jamaica Inn, the home of her Aunt Patience. There she finds Patience a changed woman, downtrodden by her domineering, vicious husband Joss Merlyn. The inn is a front for a lawless gang of criminals, and Mary is unwillingly dragged into their dangerous world of smuggling and murder. Before long she will be forced to cross her own moral line to save herself.