Always a Witch by Carolyn MacCullough
The adventures of Tam and Gabriel continue with more time travel, Talents, spy work, and of course, the evil Knights.
Since the gripping conclusion of Once A Witch, Tamsin Greene discovers that her enemy, Alistair Knight, went back in time to Victorian-era New York in order to destroy her family, Tamsin is forced to follow him into the past. Stranded all alone in the nineteenth century, Tamsin soon finds herself disguised as a lady's maid in the terrifying mansion of the evil Knight family, avoiding the watchful eye of the vicious matron, La Spider, and fending off the advances of Liam Knight. As time runs out, both families square off in a thrilling display of magic. And to her horror, Tamsin finally understands the nature of her fateful choice.