In an update of an episode from the original series, Five-0 tracks a killer targeting cops… and McGarrett is next on the list.

Captain Grover is aided by McGarrett in his search for a friend who has disappeared, after it seems like he's committed murder. Kono persists in her quest to find Adam.

An escaped convict who wants Five-0 to prove his innocence abducts Danny and McGarrett; Grace punches a person at school.

When a Detroit hit man is taken out by one of his colleagues on the streets of Oahu, Five-0 is shocked to learn the killer's surprising motives. Meanwhile, Chin puts his career on the line to help Danny get the money he needs to save his brother's life.

While Five-0 hunts for a notorious criminal who has never been seen, Kono must fight for her life when she discovers the villain's identity. Also, Kono confesses to Adam that she's conflicted about their future together because of his ties to his formerly corrupt family business.

As Five-0 investigates a double homicide involving marital infidelity, McGarrett and the team recount their disastrous Valentine’s Day experiences.

Five-0 goes on a manhunt when a deliberate chemical spill enables six dangerous inmates to escape, including Kono’s husband, Adam.

Five-0 must go up against an aggressive U.S. marshall, Lincoln, when a man wanted for murder escapes capture and seeks asylum in the sovereign land belonging to the Nation of Hawaii.

When Danny is shot while quarantined in the hospital with McGarrett, Tani and Junior, he's left unconscious and clinging to life, imagining a future for everyone in Five-0.

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.

McGarrett crosses the line and is arrested while investigating the death of his former SEAL buddy, who died while making an emergency landing on an aircraft carrier, and the only survivor is a baby. Also, Adam returns to Oahu with some devastating news about his marriage.

While investigating Flippa’s friend’s murder, McGarrett and Grover uncover a deadly plan by an extremist group on the Island. Also, Grover has an emotional reaction to the case.

Fugitive hacker Aaron Wright resurfaces to ask Five-0 for help when his co-workers at the NSA, which he has been working for, are all murdered. Also, Junior speaks at the parole hearing of the drunk driver who killed his sister.

Five-0 enlists imprisoned hacker Aaron Wright to help when a young girl is reported kidnapped, but upon rescue, the culprits are dead, the girl is safe, and she's not who she claims to be.

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