From the Back Cover:
Judgement Day is an intriguing investigation for a team of 2-4 Judges of average experience or 4-6 newly-appointed Judges. This package is not a complete game in itself; you will need Judge Dredd - The Roleplaying game to play this adventure.
It's two in the morning. A team of Judges glides through the deserted streets surrounding the old Maze development area, looking in vain for the occasional insomniac perp to arrest. It's a very quiet night, with few of the shift's major incidents catching the attention of the Judges as they drift over their bikes radios. The mob war is continuing to rage across the northern sectors - another two-bit gangster has been terminated by the opposition tonight. A massive new tower block has been found to be infested with Rad-Fleas, and is presently under strict quarantine while emergency Med-Squads desperately battle to fumigate the building on time. Some crazy citizen has taken it into his head to fire quided missiles at Zoom-tube trains as they pass, presumably just for the fun of it. On the whole, though, it's been quiet ....
Not very far away, though, a shadowy figure is putting the finishing touches to a plan that will put the whole of the Mega-City at risk. If the plan is allowed to succeed, the judges will once again be faced with the threat of chaos and anarchy, when the most evil criminal mind the Mega-City has ever known returns to claim what's his, on JUDGEMENT DAY!!