Monk is now a superintendent with the Thames River police and is struggling to earn the respect of his men. While on patrol near Waterloo Bridge he notices a young couple at the bridge railing. Are they embracing or is she pushed, as horrified, Monk sees the young woman fall to her death in the river. With the help of Hester, the young mud lark Scuff, Sutton the rat catcher and his dog, Snoot, Monk investigates more deaths and must race against time to prevent further tragedy…