After a werewolf slaughters the family of a pregnant newlywed, she learns a Grimm ancestral secret and becomes a cold-hearted huntress while investigating who stalks her.

This premise has much potential.

Best to remove "...while investigating who stalks her." because this is a secondary goal which subsequently dilutes the primary goal of hunting the Werewolf.

Hope this helps.

Hello,

what is a Grimm secret? I would cut this sentence since "learning a Grimm ancestral secret" means nothing for the reader (it means nothing for me).