Bloodstone - Lost Witch, #1

Family secrets hold the key to buried magic. Her legacy awaits. Katelyn Grey is a gardener in Southern California. She's content with pruning shrubs and looking after her step-mom, the only family she has left. That is, until a lawyer shows up and tells her that her long-lost aunt died, leaving her the family home on the other side of the country. Though Katelyn hates to travel, a weird clause in her aunt's will forces her to visit a quaint New England seaside town.
Her world changes when she discovers she's inherited a haunted brownstone, fickle magic, and a hidden key that someone else wants. And they're willing to kill for it. Now, she must learn how to use magic, find the key, and figure out what it's for before she ends up like her long-lost aunt. Dead.