No Turning Back by Peyton, K.M.

Passion, courage and determination burn brightly in Minna's second adventure, from a classic author. Synopsis: When Minna's true love Theo leaves the lonely fort of Othona for the big city, Minna cannot bear to be left behind and steals away on her beloved pony, Silva, to follow him. But she has no idea that her actions will condemn Theo to fight a deadly duel - with her life as the prize. Set in a beautifully atmospheric Roman world, this classic story will enchant girls looking for action, adventure and romance.