In a transmission to Cloudbase, the belligerent Frost Line commander General Ward warns Colonel White (voiced by Donald Gray) that he will fire missiles at Mars if another base is attacked. Fearing the Mysterons' response to such an action, White orders Captain Scarlet and Lieutenant Green (voiced by Francis Matthews and Cy Grant) to investigate Red Deer. Arriving at the base, the officers discover that the personnel have suffocated not due to the introduction of a toxic gas, but the removal of all oxygen from the air.