Lady Vivian Beaconsfield has disappeared following a supervised outing from Bethlem Royal Hospital. Having spent most of her adult life in and out of one asylum after another, she at last seemed to be adjusting to her confinement at Bethlem. So why did she disappear? And why is there no trace of the nurse who accompanied her? In their search for the missing women, Mary Russell and Sherlock Holmes follow the trail from the cold, harsh wards of the hospital through to the ethereal beauty of Venice. Caught up in decadent soirees, the rising tide of fascism and the myth of a haunted madhouse, the pair will discover that there are secrets hidden in the lagoon and nothing is quite as it seems.