McGarrett and Danny recruit Tani Rey to join the task force when diabolical hacker Aaron Wright releases a dangerous arsonist from prison.

Junior and Adam back up McGarrett when a bank heist in progress forces Steve to make a potentially heartbreaking mistake. Also, Adam is forced to face an empty home without Kono

McGarrett poses as a pilot to investigate a plane crash that led to the death of a pilot in an air race.

When the corpse of a diamond smuggler is stolen from a graveyard, Five-0 tracks down his partner, Voss, who will stop at nothing to retrieve their latest batch of contraband. Also, Adam recruits a new confidential informant, Jessie Nomura; Tani gets a devastating call; and McGarrett tasks Pua to find his and Danny's stolen tools.

Harry Five-0 must help Duke after he is forced to steal crucial evidence from the police locker in exchange for his kidnapped granddaughter. Also, Jerry goes undercover at a mental health facility in order to solve a murder.

Thanksgiving brings Grover’s parents and brother Percy Jr. to Oahu for a visit tainted by sibling rivalry, and Five-0 investigates a thief who is crushed to death by an empty safe.

MacGarrett and Five-0 support Danny and Rachel by determining what happened when gets into a life-threatening car accident and lands in critical condition. Also, Tani helps Koa when his rehab patient goes missing.

Five-0 must locate a teen girl who purchased a gun from a junkie, and discover that the firearm, over the course of decades, has affected all of their lives.