"An encounter with an anti-gravity machine catapults Peter Schock and Kate Dyer back to the 18th century and sets in motion a calamitous chain of events. While a massive police hunt gets underway to find the missing children in the 21st century - in 1763 a hardened criminal, the Tar Man, steals the anti-gravity machine and disappears into the London underworld. Stranded in another time and forced to chase the Tar Man to his lair, Peter and Kate find a friend and guide in reformed cutpurse, Gideon Seymour. Gideon does every thing he can to help them, but will his dark past catch up with him before the machine is recovered?"
The Time Travelers, Book 1 by 
The Time Thief, Book 2 by 
The Time Quake, Book 3 by