The Dupayne, a private museum on the edge of Hampstead Heath, is dedicated to the years 1919-1939, and one of its galleries displays exhibits from the most notorious murder cases of that period. After one of the trustees is horribly murdered, Dalgliesh and his team establish that each of the small group of people who run or work at the museum has the means and the opportunity for murder. But one of them had the ruthlessness to kill and kill again, the crimes uncannily echoing the cases on display in the Murder Room.
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