Danger Within (movie, 1918)

A ruthless, miserly millionaire wakes up one day and finds that a quarantine sign reading "Danger Within!" has been tacked onto the front door of his mansion, and guards have been stationed outside to make sure that no one enters or leaves the building. The only other person in the house is Dolly, his chief clerk's six-year-old daughter, who went into the house out of curiosity just before it was quarantined.