A mix of a historical mystery and a legal thriller. The pleasure boat was blown up by the dynamite. 200 people died as a result of it, killed during the explosion, drowned in the river, and perished from pneumonia or sustained injuries. William Monk, the commander of the River Police and a direct witness of the tragedy, first helped in the rescue efforts, then started investigating the incident. But the very next day the investigation would be taken over by the Metropolitan Police, despite the fact that the explosion happened on the Thames and should have remained in the jurisdiction of the River Police. What will happen next are judicial procedures and efforts in uncovering the mystery behind the tragedy. 
 Although all the favourite characters have their cameos or bigger parts, this novel is less absorbing than previous books in the Monk series. The judicial procedures take quite a big part, but are less personal when there is no Rathborne to defend, prosecute or judge, just assist in the second trial. Because of the various circumstances both Monk and Hester are less involved in the investigation than in previous books of the series. When the mystery is finally resolved, it is a bit anticlimactic and rushed. Nevertheless, it still makes a good reading, especially when combined with a mug of tea and a plate of biscuits.:)