To Deepen the Heart and Commit A Crime

So I'm writing a scene between one of my favorite characters and another guy. Thus far, the guy asked to look at a wound on the girl's ankle while she held a hunting knife firmly in her hand. She had stolen the knife and had been keeping it tied around her ankle, but she didn't have the sheath, so when she would sleep or walk, the knife would cut into her skin. Anyway, so this guy says the wounds are too "scabbed-over" to treat effectively with any kind of homeopathic medicine, so they're just kind of sitting there, enduring the silence. Then he complements her on her hunting skills, and she relates how she learned most of it on her own, but her father taught her certain things, like archery. It's a very touching/revealing scene because the character (the girl) is extremely reclusive, so the fact that she is talking to this person so freely without feeling conflicted or saddened is a huge step for her.
So that's that scene. But now I want to write this other one for the same story, just between three different characters, all of whom are crucial to the story itself. The first two, twin sister and brother, live with an innkeeper and his wife (very Les Miserables, don't you agree?). The brother is trying not to anger the innkeeper as the latter has a short temper. The former is sent to wait on a customer, who upon seeing him finds him very mysterious indeed. (Think of the scene in The Lord of the Rings: The Fellowship of the Ring where Frodo glances over to the corner and sees Aragorn, cloaked with his face hidden in darkness, the embers in his pipe illuminating his eyes briefly as he waits.) What I'm getting at is the sister is blamed for a crime she didn't commit and she and her brother flee with this Aragorn-like traveler. What I'm stumped on is the crime. What should it be? The story is set practically in the Dark Ages, so stealing is too hum-drum. Murder?... Eh, maybe. Heresy! Ooh, possibly. Maybe witchcraft, but probably not. Ooh, ooh, ooh! She should be blamed for causing a plague or blight in the village and the brother and traveler rescue her at the last minute, making them immediate fugitives!
Ah! I must go. I must write!

-Grace