Tom Derringer in the Tunnels of Terror - The Adventures of Tom Derringer, #2

A would-be conqueror had accused Tom Derringer of being a part of Gabriel Trask's cabal of spies and assassins. Tom had never heard of Gabriel Trask. The experts of the Pierce Archives knew only that Mr. Trask had some connection with the late Emperor Norton, self-proclaimed Emperor of the United States and Protector of Mexico, so Tom set out across the continent in pursuit of the truth. Did Trask truly control spies and assassins? And if so, had Tom made himself their target? Someone was certainly taking an unwelcome interest in Tom's activities...