As the team investigates two spooky cases, one involving a serial killer and the other involving a raid at a blood bank, Danny is dealing with something even scarier in his personal life: His daughter, Grace (Teilor Grubbs), is getting too old to spend the holiday with her dad. (Fortunately, he'll have his son Charlie to keep him company.)
"Danny's daughter escapes to go to a party with kids that are a little bit older than her," executive producer Peter Lenkov tells TVGuide.com. "He goes and hunts her down and has to extract her from this party. There's a little bit of a rift between daughter and father in that."
As far as the cases are concerned, the show will stick with the Halloween theme and pay homage to the legends of Dracula and Frankenstein, with horror maestro Joe Dante (Gremlins) returning to direct the episode.
"We do a Halloween episode every year, and I think every year we try to outdo ourselves in the scary department. I think this year definitely is the scariest we've done," Lenkov teases. "We try to root them as much as we can in reality, and try to debunk the myths of Frankenstein and Dracula."
Check out an exclusive sneak peek above.
Hawaii Five-0 airs Fridays at 9/8c on CBS.
(Full disclosure: TVGuide.com is owned by CBS.)