Harlequin (The Grail Quest, #1)

by Bernard Cornwell

Jeanette shot him a vicious look. ‘You once swore to me,’ she said, ‘that you would help restore my son to me.’ Thomas made the sign of the cross again. ‘I did, my lady,’ he admitted, reflecting that he made his oaths too easily. One oath was enough for a lifetime and he had made more then he could recall or keep.