The Double Life

Lumley leads a double life as a respected, cultured gentleman and a master criminal, while Pitt-Heron flees under a secret identity, and Leithen himself must operate covertly, maintaining his normal routine while engaged in a dangerous investigation.

Leithen hints at a hidden, exciting role he played from his ordinary London chambers, suggesting a secret life.

Pitt-Heron's secret activities and the contrast between his public persona and hidden dealings.

Pitt-Heron hides a secret laboratory and a circle of foreign contacts, leading a double existence beneath domestic respectability.

Lumley's use of Pavia's house and the possibility of impersonation hint at a double identity and concealed motives.