You could call it a sequel to Trifecta if you liked, but it's really the culmination of a storyline that's put its roots in the years of Chief Judge Cal and the Apocalypse War. There's someone called Judge Smiley. Yes, feel free to think of John le Carre. He's a quiet, bespectacled man. Quite boring. He's lived for years in a small house in the Justice Department and no one ever sees him coming or going.
Anyone who attracts his attention is likely to die. He's working for the sake of the Justice system, but he's been killing so long and with so little oversight that his idea of the "greater good" has become idiosyncratic.
I'd never seen a Judge Dredd story like this before. The two opponents (Smiley and Dredd) are both inside the system, but operating against it. Dredd's in more danger, though. Smiley's been working so long that he must have some kind of official sanction. Does the Chief Judge know? Has she authorised all this? Quite possibly. Hershey tolerated Bachmann, after all, and it's hard to see much difference between the covert assassination campaigns of Smiley and Bachmann. Black ops were Justice Department policy. As Smiley says, "We're fascists."
Smiley's evil. That's a no-brainer. However, it's a dull, pragmatic kind of evil that tries to avoid stirring heroism, exciting battles or any of the other tropes of villains in an adventure comic. Dredd can only win by outthinking Smiley, which is alarming because that's Smiley's forte, not Dredd's. You can't even find or meet Smiley unless he's chosen to permit it. If he thinks you're a threat, there won't be a thrilling confrontation and your death won't be dramatic. You'll just be found one morning with your throat slit. He has a reason for all his actions and can explain himself rationally.
The other thing I really like here is the characterisation of Dredd himself. Yes, that's right. Most writers wouldn't even consider going there. There's no taboo on trying, but the guy's been a one-dimensional bastard for decades and you'd think exploring his characterisation would be like deep-sea diving in a puddle. Nonetheless, Rob Williams does it and it works. He examines what kind of person Dredd is and it feels both true (because it is) and new (because we're not used to this). "He swallowed down the urge to beat what he needed out of the Sov."
This story is shocking. "Blondel Dupre's on that list." It's got a body count, including fan-favourite characters. It's both good and interesting. It's not as mad or exciting as better-known epics and you probably wouldn't choose this for a newbie's introduction to Dredd's world, but it's excellent.