The Time Travelers, 1

Gideon Seymour, thief and gentleman, hides from the villainous Tar Man. Suddenly the sky peels away like fabric and from the gaping hole fall two curious-looking children. Peter Schock and Kate Dyer have fallen straight from the twenty-first century, thanks to an experiment with an antigravity machine. Before Gideon and the children have a chance to gather their wits, the Tar Man takes off with the machine -- and Peter and Kate's only chance of getting home. Soon Gideon, Peter, and Kate are swept into a journey through eighteenth-century London and form a bond that, they hope, will stand strong in the face of unfathomable treachery.