The Cain Saga

Cain C. Hargreaves is a cursed count with a... strange... obsession; he collects poisons, as his family has done for many generations before him. With his knowledge of such things, he helps to solve crimes in 19th century England, which seem to follow him everywhere; thus, the Hargreaves family curse. Eventually, the crimes he solves all seem to point to one organization as their benefactor; Delilah. As Cain runs into Jezebel Disraeli, Delilah's representative, more and more, he comes to learn that the organization was founded by none other than Cain's father, who was, until oh-so-recently, thought to be desceased. Fueled by a reawakened hatred for his father, Cain tries to do everything in his power to help the victims of Delilah's evil-doings.

Source: Anime News Network Encyclopedia