In a flashback, Deborah Myers (Sheri Moon Zombie) visits her son, a young Michael Myers (Chase Wright Vanek), at Smith's Grove Sanitarium. She gives him a white horse statuette as a gift, which Michael says reminds him of a dream he had of Deborah's ghost, telling him she was going to bring him home.
One year after the events of the first film, Laurie Strode (Scout Taylor-Compton) is now living with the Bracketts. Michael has been missing since last Halloween and is presumed dead, while Laurie has been having recurring nightmares about the event. Meanwhile, Michael's psychiatrist Dr. Sam Loomis (Malcolm McDowell) has chosen to turn the event into an opportunity to write another book. Elsewhere, Michael, who is still alive, has been having visions of Deborah's ghost and a younger version of himself, who instructs him that it is time to bring Laurie home, so he sets off for Haddonfield.
As Michael travels to Haddonfield, Laurie begins having hallucinations that mirror Michael's and also begin to include her acting out his murders. Meanwhile, Loomis goes on tour to promote his new book, only to be criticized by the public, who blame him for Michael's actions and for exploiting the deaths of Michael's victims. When Loomis' book is released, Laurie discovers that she is really Angel Myers, Michael's long-lost sister. She goes to a party with Mya (Brea Grant) and Harley (Angela Trimbur) to escape how she is feeling. Michael appears and kills Harley, then goes to the Brackett house and fatally wounds Annie Brackett (Danielle Harris). When Laurie and Mya arrive, Michael kills Mya and then comes after Laurie, who manages to escape. Laurie flags down a car, but Michael kills the driver and flips the car over with Laurie still inside. Michael then takes the unconscious Laurie to an abandoned shed.
The police discover Michael's location and surround the shed. Loomis arrives and goes inside to try to reason with Michael. Inside, he finds Laurie, who is hallucinating a younger Michael holding her down, and tries telling her that no one is restraining her. Just then, Deborah instructs the older Michael that it is time to go home; Michael attacks Loomis and kills him. Stepping in front of a window while holding Loomis' body, Michael is shot twice by Annie's father, Sheriff Leigh Brackett (Brad Dourif), and falls into the spikes of some farming equipment. Apparently released from her visions, Laurie walks over and tells Michael she loves him, then stabs him repeatedly. The shed door opens and Laurie walks out, wearing Michael's mask. Later, Laurie sits in isolation in a psychiatric ward, grinning at a vision of Deborah.
In 2008, at the 30 Years of Terror Convention, Halloween producer Malek Akkad confirmed that a sequel to Rob Zombie's 2007 film was in the works. French filmmakers Julien Maury and Alexandre Bustillo were in negotiations to direct the sequel in November 2008, but on December 15, 2008 Variety reported that Rob Zombie had officially signed on to write and direct the Halloween sequel. In an interview, Zombie expressed how the exhaustion of creating the first Halloween made him not want to come back for a sequel, but after a year of cooling down he was more open to the idea. The writer/director explained that with the sequel he was no longer bound by a sense of needing to retain any "John Carpenter-ness", as he "felt free to do whatever". Producer Malek Akkad said the original intention, when they believed Zombie was not returning, was to create a "normal sequel". Akkad and his Trancus producing company hired various writers to come up with drafts for a new film, but none worked. Akkad and the Weinstein brothers then turned to Bustillo and Muary, whose film Inside had recently been bought for distribution by the Weinstein Company. According to Akkad, the producers really wanted Zombie to return, as Akkad felt that there was something "lost in the translation" when the French filmmakers took over the project. After his work on the 2007 remake, Zombie had earned the trust of Akkad, who told him to ignore any rules they had set for him on the previous film. Akkad said that he wanted Zombie to move the franchise away from some of its established rules.
For the sequel, Mane, McDowell, Taylor-Compton, Harris, Moon Zombie, and Dourif returned to the roles of Michael Myers, Dr. Loomis, Laurie Strode, Annie Brackett, Deborah Myers, and Sheriff Brackett, respectively. Daeg Faerch, who portrayed a young Michael Myers in the 2007 remake, was set to reprise his role for Halloween II. By the time production was getting started for the sequel Faerch had grown too big for the part. Zombie had to recast the role, much to his own dismay, because Faerch's physical maturity did not fit what was in the script. Although Faerch is not in the sequel, the first trailer for Halloween II contained images of Faerch. Zombie pointed out that those images were test shots done and were not intended to be in either the trailer or the film.
Taylor-Compton described her character as having "these bipolar moments", where her emotions are spontaneously changing from points of happiness to agitation. The actress stated that Zombie wanted to see Laurie Strode travel into "these really dark places". Taylor-Compton clarified that when the film starts Laurie is still not aware that Michael is her older brother, and as the film progresses more and more pieces of information are given to her and she does not know how to deal with them. The actress explained that the darkness brewing inside Laurie is manifested externally, generally through her physical appearance and the clothes she chooses to wear—Zombie characterized the look as "grungy".
Zombie further described Laurie as a "wreck", who continually sinks lower as the film moves forward. Even Sheriff Brackett goes through changes. Brackett, who receives more screen time in this film, allows Laurie to move in with him and his daughter after the events of the first film. Zombie explained, "He's old, he's worn out, he's just this beat-down guy with these two girls he can't deal with." Zombie characterized Loomis in the sequel as more of a "sellout", who exploits the memories of those who were killed by Michael in the 2007 film. Zombie explained that he tried to channel Vincent Bugliosi, a lawyer who prosecuted Charles Manson and then wrote a book about it, into Loomis's character for the sequel; noting that he wanted Loomis to seem more "ridiculous" this time. As for Michael Myers, the character is given almost an entirely new look for the film, which is being used, according to Taylor-Compton, to illustrate a new emotion for the character as he spends much of his time trying to hide himself. Zombie said that of all of the characters that return in the sequel, Michael is the only one that does not change: "All the other characters are very different. Laurie; Loomis; they're having all kinds of problems in their life, but Michael just moves along. Michael is no different; he's exactly the same as he was ten years old and he killed everybody [...] He has no concept of the world around him, so he can never be affected by it."
With a $15 million budget, production began on February 23, 2009 in Atlanta, Georgia. Zombie acknowledged that filming in Georgia provided certain tax breaks for the company, but the real reason he chose that location was because the other locations he was planning to use were still experiencing snowy weather. For him, Georgia's landscapes and locations provided the look that he wanted for his film. During production, Zombie described the sequel as being "Ultra gritty, ultra intense and very real" and said that he was trying to create almost the exact opposite of what people would expect. Known for filming multiple sequences during production of his films, Zombie filmed an alternate ending to Halloween II. In the alternate ending, Loomis and Michael crash through the shed the police have surrounded, and out into the open air. As Loomis grasps at Michael's mask, and pleads for him to stop, Michael stabs him in the stomach, telling him to "Die!".
For the sequel, Zombie only used Carpenter's original theme music in the final scene of the film, though the director admits that he and music composer Tyler Bates tried to find other places to include it. According to Zombie, Carpenter's music did not fit with what was happening in the film; whenever he or Bates would insert it into a scene it "just wouldn't feel right" to the director. Zombie also used popular culture songs throughout the film, with "Nights in White Satin" appearing the most prominently. Zombie chose songs that he liked, and that would enhance a given scene within the film. An official soundtrack for the film was released on August 25, 2009. In addition, an album featuring the music of psychobilly band Captain Clegg and the Night Creatures was released in conjunction with Halloween II on August 28, 2009. Captain Clegg and the Night Creatures is a fictional band that appears in Halloween II. Nan Vernon, who recorded a new version of the song "Mr. Sandman" for the end credits of the 2007 remake, recorded a cover of "Love Hurts" for Halloween II.
Dimension Films released Halloween II in North America on August 28, 2009 to 3,025 theaters. Following that, the film was released in the United Kingdom on October 9, 2009. Dimension re-released Halloween II in North America on October 30, 2009 to coincide with the Halloween holiday, across 1,083 theaters. The film was released on DVD and Blu-ray on January 12, 2010; the theatrical cut and an unrated director's cut, which Zombie says is "very different from the theatrical version," are available.
On its opening day, the film grossed an estimated $7,640,000, which is less than the $10,896,610 Zombie's 2007 remake pulled in during the same weekend of August. By the end of its opening weekend, Halloween II had grossed $16,349,565. That weekend earned more than the entire box office performances of Halloween 5: The Revenge of Michael Myers ($11,642,254), Halloween III: Season of the Witch ($14,400,000), and Halloween: The Curse of Michael Myers ($15,116,634), in unadjusted dollars. The film dropped 64.9% in its second weekend, only grossing $5,745,206 and slipping from third to sixth place. Grossing just $2,114,486 in its third weekend, Halloween II dropped out of the box office top ten to fourteenth place. The re-release of the film was intended to take advantage of the Halloween holiday, but the film only brought in approximately $475,000. By the end of his theatrical run, Halloween II grossed a total of $33,392,973 in North America, and an additional $5,925,616 overseas for a worldwide total of $39,318,589. Compared to the other Halloween films, the 2009 sequel sits in fourth place, just behind the original Halloween.
Based on 73 reviews collected by Rotten Tomatoes, Halloween II has an overall 19% approval rating from critics, with an average score of 3.7 out of 10, with the general consensus reading "Zombie shows flashes of vision in the follow-up to his Halloween reboot, but they're smothered by mountains of gore and hackneyed, brutal violence." Rob Nelson, of Variety, felt the use of Deborah and the white horse was nothing more than "silly", and he disagreed with Zombie's choice to film Halloween II in 16mm film, as opposed to wider format of 35mm that he used on his 2007 remake. Nelson also stated that the hospital scene was nothing more than a "butcher"-version of Carpenter's 1981 sequel, with the rest of the film feeling like it was rushed and "slapped together" at the last minute. In contrast, Time Out believed the hospital scene at the start of the film "[bested the 1981 sequel] in just about every respect". Time Out stated that Compton's portrayal of Laurie Strode showed an "intense, nontrivializing dedication to the role" that kept interest, while the storyline of Dr. Loomis's egocentricity hinders the overall storyline. Time Out also said that Zombie hurt the film by trying to show how "violence lingers with, and perverts, all who are touched by it", but then undercutting himself with "carnivalesque" violence. Although the New York Post's Kyle Smith did not believe the character of Laurie Strode was a balance for Michael Myers or Dr. Loomis, he agreed the ghostly images of Deborah Myers were a "relief from the blood-streaked brutality" of Michael's murders.
The Boston Globe's Tom Russo had varied reactions to the film. Russo pointed out that Zombie attempted to be more inventive with Halloween II, but only achieved mixed results for his efforts. Russo referred to the dream sequences of Deborah Myers and the white horse as "pretentiously silly", but agreed that the scenes did help to break up the standard genre violence and even went so far as to compare the sensation created by those scenes to "Tim Burton doing straight horror". In the end, Russo claimed that "only the most hardcore fans" would want the film series to continue. Joe Neumaier, of the Daily News, stated that Zombie has found himself with Halloween II. Neumaier describes the film as a successful "'character-based' monster-flick". Zombie's use of music from the 1970s, like The Moody Blues' "Nights in White Satin" and 10cc's "The Things We Do for Love", is "terrifically odd" throughout the film. Neumaier also said that the imagery of Deborah Myers and the "ethereal white horse" were a "nice visual relief" from Michael's violent attacks.