Our villain throws all his belongings together and shoves his hat onto his head. He shrugs into his coat and glances around the room to make sure he hasn't left anything important behind. Once he's satisfied, he lights a candle with the new matches he's demanded of the innkeeper and kneels on the floor. What he's about to do is something he's never done before, but he's thought it carefully through. It's risky, but it's worth it. And, if all else fails, the inn will burn down, which is almost as savory an outcome.
Our villain hunches close to the floor and, using the candle, sets the floor afire. As soon as he's done so, he pauses for a moment, then stands up and stamps the fire out. But he's done so in an orderly fashion - the fire has burned a diagonal line in the floor. If he can, he'll burn plenty of lines in the floor so that they form a word.
After repeating his actions many times, our villain steps back to examine his work. The letters he's burned in the floor are ill-formed, but still legible. That's all he needs.
It says, "Confess." That's all it says. Granted, the letters are all angles - completely different from his usual style of writing - but who cares? He certainly doesn't.
He heads downstairs.
Upon seeing our villain, the innkeeper rushes out to fetch our villain's horse. He probably assumes our villain is leaving town.
In fact, he's about to make a public appearance.