Dr. Yu Tsun is a Chinese professor of English acting as a spy for Germany during World War I. He possesses vital intelligence regarding a British artillery park and needs to transmit this information to his handler in Berlin. A self-described timid man, he undertakes his dangerous mission to prove his competence and valor.

Dr. Stephen Albert is an English Sinologist living in the village of Ashgrove. He dedicates his time to studying Chinese culture and translating a complex ancient manuscript. His scholarly work gives him unique insight into unconventional philosophies of time, reality, and branching futures.

Captain Richard Madden is an Irish agent working for the English government. He relentlessly pursues enemy spies and moves with fast-paced efficiency. His cultural position as an Irishman serving England mirrors the divided loyalties seen elsewhere in the narrative.

Ts'ui Pên is a former provincial governor who retreated from public life to write an infinite novel and construct a massive labyrinth. He rejected linear concepts of time in favor of a branching model of reality. His ambitious projects continue to influence scholars long after his passing.

The Chief is a German handler stationed in Berlin who directs wartime espionage activities. He harbors prejudices against Chinese individuals, which motivates his agents to prove their worth through increasingly desperate measures.

Viktor Runeberg is a German agent operating in England. His sudden compromise sets the plot into motion and forces his allies to take immediate, drastic action to complete their missions.

Captain Liddell Hart is a British military strategist and historian compiling a chronicle of World War I. His book serves as the academic container for the primary events of the narrative, establishing a historical frame for the espionage account.

The Children are a group of unnamed youths standing on the station platform in Ashgrove. They direct Dr. Yu Tsun toward Dr. Stephen Albert's property, inadvertently instructing him to follow a traditional method for solving mazes.