On a trip to Mercury, the cadets are assigned to Major Connel, the roughest, toughest, meanest officer in the entire Solar Guard. This is much to the chagrin of T.J., who starts off by putting his foot in his month and just keeps getting in deeper. But the humor of this situation quickly turns to disaster when a technical error by T.J. puts Tom and the Major in a deadly situation and on the verge of perishing in Mercury's 700 degree heat.