He wasn't planning on getting involved. He had his own problems after all, but someone had to ask questions about the dead girl...
Ruso is an army doctor (medicus) recently arrived in early second-century Britain. The setting comes alive in all it's grittiness, and we quickly learn to care about the plight of Tilla, wonder what Merula and Bassus are really up to and despise the penny-pinching Priscus who seems to have more power than he should. A Good Read.