Complex sentence: Lisa (Gwynne Gilford) walks in on Chester in the process of being devoured by the Blob, and escapes, but cannot get anyone to believe her, not even her boyfriend Bobby (Robert Walker, Jr.).
Split into simpler sentences: Lisa (Gwynne Gilford) walks in to see Chester being devoured by the Blob. She escapes, but cannot get anyone to believe her, not even her boyfriend Bobby (Robert Walker, Jr.).