Medicus, by Ruth Downie

Gaius Petrius Russo is a down-on-his-luck army medico stationed in the backwoods outpost of the empire: Britannia. He tries to stay detached and let events roll on without him, but he just can't. He is simply too curious, and though he can't admit it, he's also too decent to let injustice go unchecked. Though he is a doctor, he investigates and solves the murders of several slaves.
audio: 12.5 hours
print: 400 pages