Poison Garden - The Elle Black Penny Dreads, #2

Faced with a vampyre once-husband returned from the dead, Elle Black, the psychic detective, flees London with her wife Faedra to answer an heiress friend's plea: what is causing the eerie change in Peasy's mother and staff? In Peaseflower estate, strange dogs roam, servants come in twins and triplets, and Peasy's scientific wonder, her immense conservatory, houses the rarest exotics and botanical treasures yet to be revealed to men-including one mysterious and highly guarded specimen.
Elle must discover what's gone wrong at Peaseflower, but the world of plants has its defenses.and horrors. When she rushes to save Faedra from a killer and the secret, uncanny presence speaking inside her mind, Elle risks madness-and poison.