A real estate agent is found dead inside the walls of one of his listings. Meanwhile, Danny's mother makes an unexpected visit and brings with her some shocking news.

A triple homicide is linked to a secret, downed Chinese satellite; Danny's mother goes on a ride-along with Grover.

A man is shot as his daughter is abducted; Danny tries to reunite his parents; Jerry finds a code on McGarrett's champ box.

While Danny’s mother is questioned by the FBI, McGarrett partners with a young man with autism who may have information to help solve the murder of his only friend.