Spirited Mary Yellan (Jessica Brown Findlay) finds herself alone in the world when her mother passes away. She is forced to move to the isolated Jamaica Inn deep in the heart of the windswept Cornish moors where she enters a world where nothing is as it first appears. Her aunt Patience (Joanne Whalley) is a shell of the carefree woman she was, firmly under the spell of her domineering husband, Joss (Sean Harris). Joss is the head of a violent smuggling gang and when he isn't smuggling, he is drinking heavily to forget all he has seen and done. Then there is the enigmatic Jem (Matthew McNulty), her uncle's brother and therefore not to be trusted in Mary's mind - although her heart may be saying otherwise... Life at Jamaica Inn challenges Mary's black and white sense of right and wrong as she finds herself living among smugglers in a lawless land. When she thinks she has witnessed a murder, Mary wonders at what cost she will stay silent.