TV-PG-V. In 1962, three 12-year-old children in a small-town, communist-phobic culture form an investigative unit into a bizarre aerial phenomenon, a military hospital with secrets, men in black, and an unsolved lethal explosion.

TV-PG-V. The base explosion causes a Red Scare, and Arthur and his new friends begin investigating those who may have been involved with the explosion.

TV-PG. Arthur and his friends Tim and Madeline look into the town's mysteries, and the police chief investigates one man's part in the base explosion.

TV-PG. Beth tries to connect with her son, Arthur, who has built a metal detector with his friends to help them investigate the mysteries in Granite Flats. A big city reporter begins asking questions around town.

TV-PG. Friendships are tested after a failed class project, Beth investigates Frank's strange behavior, and John struggles to balance his family and his duties as police chief.

TV-PG. Arthur and his friends look for more mysteries to solve. John, the police chief, works with the FBI.

TV-PG. Frank asks for Beth's help to prove his sanity. Hershel receives visitors while incarcerated.

TV-PG. John races to free Hershel from prison and the kids uncover real danger after the science fair.