Complex sentence: Pete finds Jonesy/Mr. Grey who forces him to direct and accompany him to Derry, after which Mr. Grey makes Byrus fungus constrict and kill Pete.
Split into simpler sentences: Pete finds Jonesy/Mr. Grey and Mr. Grey forces Pete to come with him, guiding him with directions to Derry. Once the directions follow through, Mr. Grey has the Byrus fungus constrict and kill Pete.