What really happened on board of the Titanic? Someone, or something, is haunting the ship. Between unexplained disappearances and eerie deaths, the guests of the Titanic–particularly maid Annie Hebley and guest Mark Fletcher–are convinced there’s something sinister afoot. But before they can unveil the danger that beckons them, disaster strikes. Years later, Annie is working as a nurse on the sixth voyage of the Titanic’s sister ship, the Britannic, newly refitted as a hospital ship. When she happens across an unconscious Mark, now a soldier fighting in World War I, Annie is relieved to see he survived the sinking. But soon Mark’s presence awakens deep-buried secrets, a creeping darkness forcing Annie to reckon with the demons of her past–as they both discover the terror may not yet be over.