An ex-Army CID officer, Mick Hardin is supposed to be retired - or he was until his sister, Linda, was shot in the line of duty, requiring him to step in as interim sheriff while she recovered. Now he's stuck in Rocksalt, the place he was most hoping to escape. Back in uniform, Mick is chafing at the sudden dissolution of his retirement plans, wearied by the petty squabbles of Rocksalt's townsfolk. It's all business as usual, until the murder of a local bar owner draws an unlikely suspect who threatens to fan the flames of Mick's past. When two more bodies turn up, seemingly unconnected to the first, Mick is forced to reckon with the mysterious circumstances of a case not so open-and-shut as everyone believes. Meanwhile, Linda is slowly healing when a familiar business tycoon with a vested interest in her returning as sheriff makes it difficult for her to remain on the sidelines.