In chapters 13-16, Mrs. Frisby learns about how her husband, Jonathan Frisby died. Nicodemus tells her that Jonathan Frisby died trying to drug the cat's food. Then, Nicodemus tells her about the rats' experience in NIMH. He tells her that they were in the marketplace, and that NIMH's truck came and captured them. They went to a labratory. Dr. Schultz was the name of the scientist doing experiments on them. They split them into groups, and gave the groups different injections. Then Dr. Schultz and the lab workers started giving them tests. They put a rat in a maze, with a shock given to the rats if the rat if they chose the wrong way, and no shock if they chose the right way. All the rats learned to go through the maze, and memorized the patterns.