Chain of Iron By Cassandra Clare

In Edwardian London, Cordelia and James navigate a fake marriage while teaming up with their friends to stop a serial killer and defeat a demonic Prince of Hell. 

This book contains: alcohol use/abuse, alternate sexual ideologies, anxiety, blackmail, body horror, bullying, child abuse, dark content, death/grief, deception, demonic content, depression, divination, drugs, dubious consent (supernatural), explicit sexual activities/nudity, gore, horror, murder, necromancy, oppression, paranoia, parental neglect, profanity, sexism, sexual dialogue, smoking, stalking, theft, torture, toxic relationships, and violence.