Time Frame - The Thomas Knight Chronicles, #3

When an elderly witch finds that people she has known all their lives have been erased from existence, she decides she must investigate. With the assistance of her tabby cat, Frank, she delves into the demon realm and soon discovers that someone has found their way back in time and whether intentionally or not, has changed the future. This temporal intruder can only be the sorcerer Balfour. The young Guardian of Magic, Thomas Knight, is summoned and without even a cup of nettle tea to keep him going, is sent back over two thousand years to the time of the ancients.
He must not only find his old enemy, bring him back to the present and undo the damage he has done to the timeline, but he must also fulfil his destiny as the celebrated hero who saves Iragoth from the greatest evil ever known. With the future of the whole universe at stake, this will be Tom's toughest challenge yet, and he will have to face it without his friends.