Quincy, D. M. (Diana). Atlas Catesby mystery.

Aristocratic adventurer Atlas Catesby has spent the last year trying to forget Lady Lilliana Warwick, but when she reappears in his life imploring him to help her solve a murder, Atlas feels compelled to say yes. The nerre-do-well brother of Lilliana's maid died of arsenic poisoning. Authorities are ruling his death an accident, but his sister suspects he was murdered. As Atlas and Lilliana investigate, they discover that the victim had a mysterious lover--a high-born lady he threatened with scandal after she spurned him. When they finally uncover her shocking true identity, the case blows wide open and it turns out there is a whole string of women who had reason to kill the handsome charmer. Now, as Atlas fights his growing feelings for Lilliana, they must work together to catch the assassin before the killer gets to them first