Complex sentence: An unforeseen result of their experiments is the ability to perceive creatures from another dimension that proceed to drag the head scientist into their world, who returns as a grotesque shape-changing monster and preys upon the others at the laboratory.
Split into simpler sentences: An unforeseen result of their experiments is the ability to perceive creatures from another dimension, who proceed to drag the head scientist into their world. He later returns as a grotesque shape-changing monster and preys upon the others at the laboratory.