 Complete the following phrase:  He appeared in the biographical epic film John Paul Jones 1959, in which Robert Stack played the title role of the American naval fighter in the American Revolutionary War. Cushing became very ill with dysentery during filming and lost a considerable amount of weight as a result. Cushing played Robert Knox in The Flesh and the Fiends 1960, based on the true story of the doctor who purchased human corpses for research from the serial killer duo 