McGarrett and Kono suspect that an abused girl may be the victim of a sex trafficking ring on the island. Meanwhile, Chin and Grover investigate a murder at a sober-living facility.
McGarrett and Danny finally track down the missing uranium, which has been built into a bomb located in the middle of the jungle. Now, they must carefully extract the unstable bomb through treacherous terrain before it detonates.moreless
McGarrett and Five-0 once again become entangled in the twisted mind games of serial killer Dr. Madison Gray when she stumbles into HPD covered in blood that matches Alicia Brown's and claims she has amnesia.moreless
McGarrett and Danny celebrate Valentine's Day with their girlfriends, while the rest of Five-0 investigates the murder of a man taking a class on how to land women.
Danny chaperones Grace's winter formal but terrorists seize the venue and hold everyone hostage in order to kidnap a diplomat's son. Also, Danny and Grover are shocked to learn that Will is Grace's secret boyfriend.moreless
McGarrett and Alicia are kidnapped by the serial killer who has been terrorizing the island after they discover his identity.
FBI profiler Alicia Brown is forced to join McGarrett in the hunt for the chess-piece killer when she finds a body in her bed. Meanwhile, Kono reconnects with a former surfing competitor who is now a disabled and homeless war veteran.moreless
Five-0 works with rogue MI-6 agent Harry Langford to find a terrorist planning to cause nuclear reactors across Europe to melt down. Meanwhile, McGarrett and Danny ask retired FBI profiler Alicia Brown to help them find a serial killer vigilante.moreless
Season 7 begins with the body of a serial killer being found in Five-0 headquarters with an ivory chess piece in his mouth. When a second serial killer is found dead with another chess piece, Five-0 hunts for the vigilante as fear spreads that it's not safe to travel to Hawaii. Meanwhile, McGarrett refuses to take it easy, even though he is recovering from surgery.moreless
In the series finale, lives are endangered unexpectedly when Castle and Beckett prepare to take on LokSat.
A psychiatric inmate escapes and drops dead in Castle's PI office, and the investigation that follows has Castle surmising the Antichrist could be involved.
A movie star who transitioned to theater work is killed, so Castle and Becket go behind the scenes to investigate what was going on in the actor's life.
A city inspector cheats death twice when he survives poisoning and electrocution attempts on his life, and a curious Castle and Beckett grow determined to solve this mysterious case.
Hayley helps an old pal, but this favor gets her in trouble, linking her to a murder and a cyber-terror attack. She then needs help herself, so Castle and Beckett attempt to clear her name.moreless
Castle and Beckett embark on a search for Aladdin's lamp after a man linked to smuggling Turkish antiques is killed.
One of Esposito's old cases is reexamined by Castle and Beckett because of a clue left at a crime scene involving an armored-car driver's murder.
The team head to the NYPD Academy for an investigation involving a murdered recruit. Meanwhile, Castle grapples with a decision with far-reaching ramifications for himself and Beckett.
Castle returns to Los Angeles in search of info about the missing time related to his abduction, and while he's there, the Greatest Detective Society reaches out to him and asks for his assistance in solving a murder.moreless
A student learning to speak English is killed and his classmates keep mum when questioned by police, so Castle goes undercover to gain info on the victim by enrolling in the class as a French Canadian immigrant.moreless
Castle gets abducted and must solve puzzles and mind games with a group of strangers. Meanwhile, Beckett and her colleagues race against the clock to find Castle and capture a killer.
A Russian diplomat's son is killed, leading Castle and Beckett to learn about international crime and foreign politics as Castle is tasked with keeping a Russian security officer busy.
Castle takes the stand as the key witness in a murder trial, but then new info emerges late in the case, leading him and Beckett to rush to prevent a miscarriage of justice.moreless
A body is found in a theater where Martha is working, so Castle and Beckett investigate and are surprised to learn how cutthroat Acappella singers can be.
An entertainer on a cruise ship is killed, and Castle and Beckett investigate while trapped on the ship with the murderer.
A seductive con man is killed, and the investigation has Castle and Beckett questioning New York City's upper crust. Meanwhile, Castle has a surprise in store for his and Beckett's one-year anniversary as husband and wife.moreless
Det. Slaughter returns seeking Castle's help in a robbery case. However, Slaughter becomes a suspect when the heist case turns into a murder case, and Castle's unsure about whether his pal is innocent or guilty.moreless
An art thief steals a rare painting and kills the person transporting it, so Castle and Beckett team up with the key witness in order to find the culprit.
A hermit-like author idolized by Castle is killed, and Castle resolves to solve the murder.
Castle goes undercover as a professor after a college fraternity student is killed in a grisly manner. During the investigation, he and Beckett unearth some sinister secrets the university wants to keep suppressed.moreless
In the conclusion of the eighth-season opener, Beckett's disappearance is examined from her angle as she fights to stay alive and uncover who wants to see her demise.