This was a excellent story in my favorite science fiction topic: time travel.
The chapters bounced back and forth between the girl in the present and the guy who got stuck in the stone age. Finally you learn about the dueling groups of time-travel scientist in different eras with a surprising twist in their techniques for doing battle. One of the things I love about time-travel novels is the wide variety of unexpected ways to cover the same topic and plot.
The two main characters were 16 year-olds, which added a twist in perspective.
Another twist (depending on your where you are from) is that it takes place in England (Stonehenge) by a British author.
I guess I'm a sucker for picturesque speech, so here are my picks:
"There was nobody in, just her dog having kittens in the kitchen." p30
"My only concern was that somebody with an equally high opinion of their driving skills might be whizzing the other way." p51
"He had a smile you could grease a cake tin with." p54
"He made Machiavelli look like Homer Simpson." p63
"Having Blaith for protection will be like being a goldfish in the care of a mad moggy with a harpoon gun." 102
(reviewed 4 days after purchase)