On Halloween, Five-0 needs to track down a serial killer inspired by Frankenstein. Jerry asks the team for help when an armed gang raids a blood bank. When Grace lies and sneaks out to a Halloween party, Danny heads out to track her down.
It’s Halloween in paradise! Vampires, dismembered bodies, and teenage angst are all in fine, terrifying form on the annual themed episode of Hawaii Five-0.
This Halloween involves a case of dismembered body parts found in the woods, complete with larvae. Max concludes that the parts actually belong to four different women, most likely tourists who a serial killer would target as easy marks. Given the subject matter, Steve is skeptical at first that Max can handle working the case since his own birth mother was the victim of a serial killer. Max is ever the professional and assures his friends he is more than up to the task. Danny’s nephew then finds an occult amulet among the victims’ personal effects which leads them to another victim, which then leads them to a pattern. The killer is picking out his victims from the airport.
Steve and Grover track down the killer and Max figures out that all of the victims’ body parts are being made up to recreate a woman their killer once loved. It’s Halloween, so why not have a Dr. Frankenstein killer? Steve and Grover go looking for the killer and Steve is violently ambushed and must fight off the monster (pun intended). Seriously though, in what universe is it a good idea to go into the creepy basement which belongs to a serial killer on Halloween? Have we learned nothing from every horror movie ever made? In the end Max is indeed reminded of his mother, but Steve reminds him that she is always with him.
In other Halloween terror tales, Jerry pays his annual pilgrimage to the blood bank dressed as Dracula. His good deed is met with gunfire when the blood bank is held up. Liters and liters of a very rare blood type are stolen, meaning that they are probably being used for someone who can’t enter a hospital without being arrested. Sorry Jerry, no vampires here. Sure enough Chin and Kono track down the blood at a veterinary clinic where a hostage situation is in full swing. What results is a particularly brutal firefight where Kono even has to stab her attacker through the heart, pun intended.
Halloween wouldn’t be Halloween without family fun; if only we could find it. Danny is even more cranky about this week’s crime because this Halloween Grace has decided to spend the holiday with her friends instead of her father. It hurts, but getting to spend his first Halloween trick-or-treating with his son has stemmed the pain a bit. So he’s fine, that is until Rachel calls to tell him that their daughter lied and snuck off to a house party on the North Shore. The teenage years are going to be rough; Danny should definitely start getting in the habit of practicing for these particular lectures. The whole drive over Danny calms himself down, trying to convince himself that his little girl is still there, but she sure doesn’t act like it when her father shows up to drag her out. Danny actually remains calm and starts off with a pretty good lecture until he and Grace get into a car accident. Their all night search for a tow truck back to the city just bonds them even more, yet Danny makes it clear that the kind of lie Grace told cannot happen again. (I’m not exactly sure how Rachel explained away the lie she told about Charlie not being Danny’s son, but that’s a story for another time.) They make it back just in time for Danny and Charlie to pass out candy in the hospital, where Danny asks his son if he wouldn’t mind not growing up
- Max Bergman always dressed up like a Keanu Reeves characters for Halloween
- Neo from The Matrix 
- Ted "Theodore" Logan from the 1989 classic Bill & Ted's Excellent Adventure. 
- Siddhartha from 1993's Little Buddha. 
- (Wearing Red jersey with a 9) The character Jotah from the 1991, Point Break. 
- Chevalier Raphael Danceny from 1988's Dangerous Liaisons 
- 'The titular character of the film John Wick 
- Charlie dresses up as a cowboy and Grace as a fairy for Halloween.
- Charlie hands out candy with Danny on the day after Halloween.
Steve McGarrett: Thanks, Max.
Dr. Max Bergman: Oh, ah.. actually, uh, there is one more thing.
Steve McGarrett: What's up?
Dr. Max Bergman: I'm just perplexed at the apparent lack of curiosity regarding my costume.
Danny Williams: (snarky) You're wearing a costume?
Dr. Max Bergman: (relieved) Ah, there it is. A pithy retort laced with just a hint of condescension. Order is restored.
Steve McGarrett: Okay, who is it? .. Oh, you want us to guess who it is.
Danny Williams: Uh, George Washington's wife.
Steve McGarrett: Martha Washington.
Dr. Max Bergman: I'm clearly one of Keanu Reeves' first film characters: Chevalier Raphael Danceny.
Danny Williams: (on his cellphone) Rachel, slow down. Slow-slow down... Where is she now? Okay, don't.. I will take care.. I'm gonna go find her, I'm gonna pick her up, and I'll take her back to the house, okay? Please, everything's gonna be fine. I will call you the second I have her. I got it. Okay? Trust me. Okay, bye.
Steve McGarrett: Is Gracie all right? What's going on?
Danny Williams: Grace, uh, was supposed to be at a sleepover at her friend's place in Kahala. Turns out she lied, and she is at a house party up on the North Shore.
Steve McGarrett: Get outta here. I got this.
Danny Williams: Are you sure?
Steve McGarrett: Am I sure? Your 13-year-old daughter is at a party on the other side of the island, Danny.
Danny Williams: Good point. Now I'm gonna kill myself.
Steve McGarrett: Don't kill yourself, she'll be fine.
- The name of the satanist in this episode is Mark Shepard. Mark Shepard is also the name of the actor who plays Crowley, a satanic character, on the TV series Supernatural.
|Steve McGarrett||Alex O'Loughlin||A former Navy SEAL and the leader of the Hawaii Five-0 Task Force.|
|Danny Williams||Scott Caan||2nd-in-command of the Hawaii Five-0 Task Force and Steve's partner.|
|Chin Ho Kelly||Daniel Dae Kim||A member of the Hawaii Five-0 Task Force, and Kono's cousin.|
|Kono Kalakaua||Grace Park||Youngest member of Hawaii Five-0, and who is Chin's cousin.|
|Dr. Max Bergman||Masi Oka||Chief Medical Examiner for the Hawaii Five-0 team.|
|Jerry Ortega||Jorge Garcia||A conspiracy expert and an associate of the H50 team.|
|Lou Grover||Chi McBride||Former leader of the HPD SWAT, and newest member of H50.|
|Eric Russo||Andrew Lawrence||Danny Williams’s nephew and a crime lab specialist.|
|Grace Williams||Teilor Grubbs||Danny Williams's daughter and first born child.|
|Kamekona||Taylor Wily||An associate of the H50 team, and owner of The Shrimp Truck.|
|Sgt. Duke Lukela||Dennis Chun||Sergeant with the Honolulu Police Department.|
|Charles Williams||Zach Sulzbach||Danny Williams's Son, and second born child.|
|Mark Shepperd||Michael Graziadei||A man who appears in the episode.|
|Lia||Brianne Howey||A woman who appears in the episode.|
|Makoa||Mike Miller||A man who appears in the episode.|
|Receptionist||Sara Malia Hatfield||A woman who appears in the episode.|
|Vet.||George Russell||A man who appears in the episode.|