T. J. Andrews & Simon Scarrow 
Invader: Sacrifice (5 in the Invader Novella Series) [EPUB ebook] 

The gripping final novella in the INVADER series, set in Roman Britain, AD 45, from Sunday Times bestselling authors Simon Scarrow and T. J. Andrews.Britannia, AD 45. Rome’s plan to establish a new friendly king over a hostile native tribe is in grave danger. A sinister new Druid sect, led by a charismatic priest, is threatening to destabilise the province and has taken several Roman soldiers prisoner. Now Optio Horatius Figulus faces his most dangerous mission yet. He must venture deep behind enemy lines in search of his captured comrades and the Druids’ secret fortress. Can Figulus stop the Dark Moon Druids from inflicting a devastating defeat against the Second Legion? Can he rescue his comrades before they are put to death in a terrifying spectacle?