The two figures had been on the bridge. He had grasped hold of her. To save her, or to push her? Murder, suicide or accident? Inspector William Monk of the Thames River Police watches helplessly as the man and woman fall to their deaths. Still feeling his way in a new post, Monk knows he must solve the mystery to gain the respect of his men. Soon both he and Hester find themselves powerfully involved in the story of the dead woman, Mary Havilland, and her quest to vindicate her father. Two months previously, James Havilland had been found dead. An engineer working for the Argyll Construction Company, he was convinced that a major disaster was about to happen in the tunnels where London's desperately needed new sewer system was being built. Maddened by his obsession, he'd apparently shot himself. Mary had never accepted that. And now she was dead too. Was it chance or more sinister than that?