Bill brings home an engineering friend, Harv Mullen. He tells the family his friend is going to stay with them for a while. At dinner that night the twins start asking questions about Mr. Mullen's past. Uncle Bill tries to change the subject. Later when Harv is out of the room, Uncle Bill lets the twins and Mr. French know that Harv was sent to prison for bribery. All of sudden they become very suspicious of him.
When Cissy gets home the twins tell her about the jailbird that is staying with them. She gets excited because she is doing a sociology assignment on integrating the criminal back into society. She runs into the den and asks Harv if she can interview him. Uncle Bill tells her they're busy and escorts her out of the room and tells Cissy to be more kind and understanding.
Uncle Bill gets Harv an interview for a job but when the employer finds out Harv was in prison he doesn't get the job.
The twins start to worry about their belongings and try to hide their valuables so that Harv won't steal them. Harv starts to notice the attitude the twins and Mr. French have towards him and decides to leave. Uncle Bill comes home and tells him he got him a job in Philadelphia. He tries to talk Harv into staying until he goes to Philadelphia but Harv says he is not comfortable there. There is a sudden crash and Uncle Bill runs into Jody's room to find him sitting on the floor next to a broken lamp. The twins tell Uncle Bill they were trying to hide their valuables from Harv. Uncle Bill is disappointed in their attitude and tells Jody he can't ever go out to play in the park again. Jody says that isn't fair and Uncle Bill points out that they are treating Harv the same way, condemning him for life even though he paid his debt to society. The twins and Mr. French realize they have been unfair and they convince Harv to stay.