It is 10 November 1944 and a young woman in a woollen coat steps off a trolley bus into the darkness of wartime London and vanishes. Sixty years later, museum curator Harry Stammers receives an intriguing invitation from Bletchley Park veteran Elsie Sidthorpe. Aided by Ellen Carmichael, Stammers sets out to discover the truth about what happened to Martha Watts. THE SHELTER tells the stories of Harry Stammers, curator at the Britain's wartime code breaking centre, Martha Watts, one of the thousands of women who worked there during the War and Arthur Wallington, who finds her sitting on an upturned crate, nursing a twisted ankle, in an air raid shelter one hundred feet below London's Haverstock Hill. Sixty years later and the search for Martha Watts leads Stammers and Carmichael to Belsize Park and the deep level air raid shelter below the Underground Station. But as they begin to unravel the truth, a chain of events convince them that somebody knows about their search. Somebody who will go to extreme lengths to stop them. For Stammers, the search for Martha Watts brings the spectre of his own mother's disappearance, when he was eight years old and the fear that it may already be too late to find her, to the fore. As the pressure builds and events spiral out of control, Stammers finally makes the link that will ultimately unravel the mystery. But as the pieces of the puzzle click into place it may already be too late for Ellen Carmichael. With the mysterious 'Stephens' determined to stop him, Stammers has twenty-four hours to find her. Convinced that he has discovered the truth about the disappearance of Martha Watts and the whereabouts of Ellen Carmichael, Stammers races again to the shelter. But, when the final confrontation comes, Stammers discovers that all is not as it seems. Introducing Bletchley Park curator Harry Stammers, THE SHELTER is the first in a three-part series of thrillers.