Complex sentence: He creeps aboard where high school students Jim Miller and Suzie Donaldson are having sex, using a hockey mask Jim scared Suzie with earlier and a harpoon gun to kill Jim and then Suzie when she tries to hide in a storage hatch.
Split into simpler sentences: He creeps aboard where high school students Jim Miller and Suzie Donaldson are having sex. Wearing a hockey mask Jim scared Suzie with earlier, Jason kills Jim with a harpoon gun and then kills Suzie when she tries to hide in a storage hatch.