Apparatus Infernum Books in Order

The Apparatus Infernum books are steampunk mysteries written by Ann Aguirre and Andres Aguirre as A. A. Aguirre. They take place in an alternate nineteenth-century England where strange inventions, spiritualism, and occult secrets sit beside police work and social class tensions.

The series begins with Bronze Gods. Inspector Janus Mikani and his new partner, Celeste Ritsuko, are assigned to investigate murders that seem impossible. Janus relies on discipline and procedure. Celeste brings different skills, a complicated past, and a willingness to notice what polite society would rather ignore.

The machinery is part of the mystery.

The books use clockwork devices, secret societies, unusual science, and supernatural possibilities, but the partnership between Janus and Celeste gives the series its center. They have to learn how to work together while dealing with dangerous cases and the assumptions other people make about them.

Silver Mirrors continues their story with another investigation and a deeper look at the larger forces operating behind the city's respectable surface. The tone is more mystery than romance, though the personal bond between the leads grows as the cases test them.

Start with Bronze Gods, then read Silver Mirrors. The two novels are best read in order because the partnership and the worldbuilding carry forward. Expect Victorian-style atmosphere, odd technology, murders that resist ordinary explanations, and detectives who are better together than apart.