Unnatural History

"The Doctor regenerated in San Francisco at the turn of the milennium. When he returns there a few years later, it seems the catastrophic events that nearly sent the whole of Earth into cosmic oblivion have taken their toll. San Fransisco was the anchor point, and a breach between dimensions has sprung up. All sorts of weird and wonderful creatures have turned up - Griffens, unicorns - and things more sinister. The Doctors companion Sam is exposed and becomes a changed person - literally. Her hair is dark, she has never met the Doctor in her life. With Fitz, he is able to convince her to help them put things right - to sacrifice herself so that the old Sam may return. For stalking the turbulent streets is the sinister Unnaturalist - a collector of genetic curios whose private collection will be much enriched by the Time Travellers..."--Publisher's description.