The Eagle (The Roman Britain Trilogy Book 1) Macmillan Publishing

An ALA Notable Children’s Book, The Eagle is the first in Rosemary Sutcliff’s Carnegie Medal-winning Roman Britain Trilogy

The Ninth Legion marched into the mists of Northern Britain—and they were never seen again. Thousands of men disappeared and their eagle standard was lost. It's a mystery that's never been solved, until now . . .

Marcus has to find out what happened to his father, who led the legion. So he sets out into the unknown, on a quest so dangerous that nobody expects him to return.

See also Volume 2, The Silver Branch (#7061) and Volume 3, The Lantern Bearers (#0379)