Witchstruck by Victoria Lamb

If she sink, she be no witch and shall be drowned.

If she float, she be a witch and must be hanged.

Meg Lytton has always known she is different; that she bears a dark and powerful gift. But in 1554 England, in service at Woodstock Palace to the banished Tudor princess Elizabeth, it has never been more dangerous to practise witchcraft. Meg knows she must guard her secret carefully from the many suspicious eyes watching over the princess and her companions. One wrong move could mean her life, and the life of Elizabeth, rightful heir to the English throne.

With witchfinder Marcus Dent determined to have Meg's hand in marriage, and Meg's own family conspiring against the English queen, there isn't a single person Meg can trust. Certainly not the enigmatic young Spanish priest Alejandro de Castillo, despite her undeniable feelings. But when all the world turns against her, Meg must open her heart to a dangerous choice. -Goodreads