Recently freed (escaped) from Bedlam, Apollo is working on restoring the garden's at Harte's Folly. The theater and gardens burned in the previous book (if memory is right). He is also living in one of the burned out areas. Lily is also living there since she is out of work and can't get a job as an actress in London (she was blacklisted by her former employer when she left to work exclusively at Harte's Folly. She writes plays for money and her brother (Edwin) sells them and they split the profits. Captain James Trevillion is working for Marcus as a bodyguard/helper for Phoebe. James is also the one who arrested Apollo.
This brings Apollo, James, Asa, and Valentine together to figure out who setup Apollo. Unsure of Valentine's motives, but in this one it appears he wants Apollo's architectural designs for the garden. He's an investor (as is Apollo). I liked that Lily was able to stand up to her brother.
Lily is AKA as Robin Goodfellow. Asa Makepeace is AKA Mr Harte, Valentine Napier the Duke of Montgomery is introduced. He collects information (for blackmail?)
I read this for Romance-opoly Past Eaves moon track