Wolf Land Series by Fiona McShane

Ireland: 1659 In the castle's keep there is a room ... And in that room there is a box ... And in that box there is ...? Sorcha Moore feels as though she has finally found her real home amongst the werewolves of Wolf Wood, but enemies may be closer than she thinks. With poisonings and attacks occurring within the wolves’ community, who can Sorcha really trust? The werewolves must discover the culprit. And if they are ever to defeat the Tolberts, then they must do it fast.