Complex sentence: When Jamie Lloyd tells her about the vision she had of Michael Myers, Tina dismisses it and goes to a Halloween party at a farm with Samantha and her boyfriend Spitz, bothered about Mike not arriving, unaware that he has been murdered by Michael.
Split into simpler sentences: When Jamie Lloyd tells her about the vision she had of Michael Myers, Tina dismisses it and goes to a Halloween party at a farm with Samantha and her boyfriend Spitz. While at the party she is bothered about Mike not arriving and is unaware that he has been murdered by Michael.