Meanwhile, at the Fitzgibbon house Mrs. Brisby overhears a telephone call between Farmer Fitzgibbon and NIMH; they have been investigating suspicious rat activity in the area and are coming to the farm the next day to exterminate the rats. Knowing she must warn the rats, Mrs. Brisby manages to escape from the cage and head for her home.
While the rats have the house suspended, Jenner sees his chance to rid himself of Nicodemus and seize leadership of the rats. Along with his unwilling accomplice Sullivan, he sabotages the pulley system, causing the house to fall, killing Nicodemus.