After being committed for 17 years, Michael Myers, now a grown man and still very dangerous, escapes from the mental institution (where he was committed as a 10 year old) and he immediately returns to Haddonfield, where he wants to find his baby sister, Laurie. Anyone who crosses his path is in mortal danger
This movie contains 88 potentially triggering events.
*spoilers*
About a third of the way into the movie it is implied the mother commits suicide (offscreen gunshot) and her baby is heard crying/screaming afterwards, presumably left alone.
The girl doesn't believe the boy when he's worried about a "Boogeyman" when it turns out that Michael is hiding behind the door, but this isn't gaslighting. Gaslighting is a manipulative behavior, she didn't know he was there.
It depends on what version you decide to watch. If you watch the theatrical release, the graphic rape scene was cut from the movie so they could get an R rating. Uncut, unrated directors cut was going to be stamped with NC-17 so it was pulled from rating submission, however, so it isn't rated. Don't be fooled by that. Other commenter gave a time stamp, but you can also start skipping forward when you see two men dragging a female patient down the hall. The scene adds nothing to the plot.
The director's cut includes an explicit r*pe scene. The guards in the facility where michael is held bring an inmate in his room and force themselves on her. It is graphic.
A character is clubbed to death with a baseball bat. We don't see actual impact, there is audio and we see the damage once the character is dead, which is fairly graphic.
Michael kills his (crappy) stepdad in his first murder spree, and his mom later kills herself.
Adult Michael later kills Laurie's adoptive parents as well.
Baby screams/cries loudly several times throughout. First is at the start of the movie in response to parents fighting, and later, *spoilers* in response to the self-inflicted gunshot which kills the mother.
Mike Myers (step?)father makes very transphobic comments towards him, saying that he’s going to grow up to cut off his genitals - he then calls him Michelle.