Hawaii Five-0

A new ally helps McGarrett and the team when mob bosses on the island are targeted by an assassin; the team says goodbye to one of its own.

Tani and Junior must plot an escape for themselves and several civilians after they become trapped inside a deadly tunnel collapse; Eddie the dog sniffs out a bomb that has been planted in McGarrett's home.

A plane that mysteriously crashed into the Pacific in the '80s is found, but with a recently murdered scuba diver inside; McGarrett and Quinn zero in on who planted the bomb in his garage; McGarrett formally asks Quinn to join the team.

Five-0 enlists imprisoned hacker Aaron Wright to help when a young girl is reported kidnapped.

The team investigates a home invasion that turned deadly after a dangerous "monster" escaped from the basement; Max returns to Oahu with a very special guest.

A deadly hit-and-run involves a driverless car carrying heroin; Tani and Quinn are stuck with a pair of YouTubers who are brought on a ride-along.

When the CIA informs McGarrett that his mother has gone rogue on her undercover mission and may have killed her partner, Steve goes to Mexico to bring her home and prove her innocence.

The team searches for a killer whose plane crashed in the jungle with $10 million worth of heroin on board; Grover is thrilled when his niece Siobhan comes to try out for the University of Hawaii basketball team.

Junior and Tani track down the thief who robbed his parents' home; Five-0 investigates the murder of a beloved philanthropist and the theft of his valuable koa tree; Danny moves in with McGarrett.

When Adam's girlfriend is kidnapped right in front of him, he shuts out Five-0 and breaks all the rules in order to get her back; the team investigates three seemingly unconnected homicides.

A tourist helicopter is shot down by a missile; a search for stolen artillery leads to a ghost from McGarrett's past -- Wo Fat; Adam makes a bold decision about his future with Five-0.

When a list of undercover CIA agents is stolen, the team enlists the help of Magnum, Higgins, Rick and TC to get it back and protect national security; Higgins gives Tani some personal advice.

Grover and the team investigate a murder at a private golf course involving a man who was frozen to death in the locker room's cryotherapy chamber; McGarrett tags along with Danny when he tracks down the father of a boy who has been bullying Charlie.

Soon after Danny meets the girl of his dreams, they get into a potentially fatal car accident in an area far from help; McGarrett enlists Quinn and Tani to help when Eddie the dog suddenly shows signs of post-traumatic stress disorder.

When Grover's niece goes missing from the police academy, it's discovered that her boyfriend is an undercover member of the yakuza.

On Valentine's Day, Tani and Noelani are held hostage during a convenience store robbery; the team investigates the murder of a Thai diplomat whose wife confesses to the crime, but Danny suspects she's covering for the real killer.

Harry Langford helps Five-0 investigate some murders that follow the plot of a fabled, unpublished crime novel from the 1920s; Tani and Junior's friendship takes a meaningful new turn.

The team investigates a murder on a cargo ship where pirates impersonated the Coast Guard to board the boat; Adam finally gets the evidence he needs to take down the island's Yakuza operation once and for all.

A rancher is murdered after he uncovers human skeletons where legend says that Civil War-era gold coins are buried; Quinn's former stepdaughter reaches out to her for help after her father doesn't come home.

The team investigates a scheme to rob tourists; Tani helps Girard Hirsch prove the innocence of his elderly uncle when he's suspected of murder; Tani and Junior work on the nuances of being in a new relationship.

After Steve receives a posthumous letter from his mother that contains a cypher, Danny is attacked by someone willing to kill to steal it; Five-0 must help an anonymous good Samaritan who's in the crosshairs of some very dangerous people.

Danny is abducted and badly wounded by Wo Fat's wife, who is after the cypher Steve's mother left him; Steve finally solves the case his father left for him 10 years ago.