Q.E.D.

The Great Motor Race

Deverill is alerted to a cross-country automobile race for which he lends his talents to one of the entrants. Kilkiss also assists one of the foreign entrants.

Infernal Device

Deverill is contracted to develop a safer detonation mechanism for mining. Meanwhile Jenny and Phipps are kidnapped at a soup kitchen as a way to pressure Deverill into using his invention for political purposes.

The 4:10 to Zurich

After discovering a potent nerve agent, an associate of someone with whom Deverill has been working is shot on Deverill's doorstep. With his dying breath, the man gives Deverill a clue about a train to Zurich.

To Catch a Ghost

Jenny visits her sick aunt, from whom she learns of a potential ghost haunting the residence. She then enlists Deverill to come investigate.

The Limehouse Connection

A series of unexplained deaths among Chinese workers in London leads Charlie and Deverill to investigate. The investigation complicates when British and US officials get involved.