Honor Bound(Witch Born‪)‬

From USA Today bestselling author C. J. Archer, this romantic historical mystery will take your breath away.
Seven years ago a woman with too many secrets and a man with too many lies fell in love. Then she left him.
Isabel's quiet life as an assistant to one of London's famous apothecaries hides a deadly secret. A secret that could see her put on trial for witchcraft if the authorities uncover the truth. But when the authority figure who turns up at her shop is Sir Nicholas Merritt, she's at risk of losing more than her life. She could lose her heart and soul, and the man she loves.
Royal spy Sir Nicholas Merritt can't believe his luck when he stumbles upon Isabel during an investigation. He's been searching for her for seven long years and now he has her again, in his bed and his life. Except she's resisting all the way. Worse still, she's somehow tangled up with a plot to assassinate the queen. To hold onto her this time, he must find out why she left him while hiding a secret of his own that could tear them apart forever.