After the death of leading haematologist Professor Anstruther, antiquarian book dealer Anthony Sparrow is tasked with clearing out his mansion of its books and papers. He soon begins to question the real circumstances of the old man's death: was he in fact murdered, and if so, who was responsible?

The answer might be found in the personal diaries and letters which Sparrow unearths. But as he closes in on the answer, the perspective suddenly shifts and everything which he was sure about dissolves into darkness and shadows.