London, 1884.
125 Gower Street, the residence of Sidney Grice, London's foremost personal detective, and his ward March Middleton, is at peace. Midnight discussions between the great man and his charge have led to a harmony unseen in these hallowed halls since the great frog disaster of 1878.
But harmony cannot last for long. A knock on the door brings mystery and murder once more to their home. A mystery that involves a Prussian Count, two damsels in distress, a Chinese man from Wales, a gangster looking for love, and the shadowy ruin of a once-loved family home, Steep House . . .