In this the seventh book in the chronicles of Adam Black

Adam is larking about with his mates in Anglesey when he finds himself back in about 150 BC in a Celtic village. From his capture and enslavement until his eventual return to his own time he has a roller-coaster ride crossing Ireland as well as being on one of the first Atlantic crossings to the Azores and on to a new and exciting land.

Other Books in the series:

Book 1 A Roman Odyssey
Book 2 A Viking Voyage
Book 3 A Nazi Nightmare
Book 4 A Voyage to Victory
Book 5 A Cavalier Canter
Book 6 An Egyptian Escapade
Book 8 Fast Forward to a New Beginning