The Wolf Witch. The Ingenious Mechanical Devices, #6

Since returning to England from abroad, Emmeline Jardine has managed to get a place of her own, maintain a tenuous truce with her guardians, and celebrate her new found freedom by attending as many parties as she can manage. That is until a man claiming to be her father shows up. Her father has a problem. Her half-brother, Wesley, has disappeared while investigating possible werewolf sightings, and he needs Emmeline's help finding him.
Emmeline reluctantly agrees only to find there are others interested in Wesley's plight. When she receives a mysterious invitation to a country estate deep in the woods, Emmeline is shocked to find a familiar face there. Nadir Talbot, Decadent, writer, and all around nuisance, infuriates her to no end, but Emmeline soon finds he is the only she can turn to as they are thrust into a world of werewolves, monsters, and secrets from her family's past that threaten to bring the empire to its knees.