Darkness is My Friend - S6.E16

On a dark and stormy night, Laura and Mary are staying alone at the School For the Blind when they are taken hostage by a trio of escaped convicts. One of the criminals is badly injured, and his cohorts demand to see a doctor. Laura is sent to get Dr. Baker, warned that the consequences will be deadly if she tries any tricks. However, a terrified Laura tells her Pa what is happening. Charles shows up posing as Dr. Baker, but when the real Dr. Baker arrives, Charles is forced to be resourceful to disarm the crooks.