What are the motifs in The Daughter of Time by Josephine Tey?

People's true selves and deception are both recurring ideas. We learn that Alan Grant is a caring person through glimpses of his gifts to Mrs. Tinker, his affection for Sergeant Williams and Brent Carradine, and his affection for his nurses and caretakers. He is presented as a tough investigator who was chasing a criminal when he fell through a trap door. He is humiliated by this and somewhat angry at being in this confined situation, but it turns out that he is quite a pleasant man.