All the way back from September 2002 Trapped on Titan was written by Jonathan Clements and directed by John Ainsworth.
Dredd has to go undercover as a criminal on the penal colony on Jupiter's moon, Titan. He has had a face change procedure so none of the perps will recognise that distinctive chin, and so the writers can get round him not wearing his helmet. Titan, of course, has special significance for Dredd because it was where his clone brother Rico was sent after he became a corrupt Judge. And much of the plot centres around the prisoners searching for the mythical Rico's rock which is seen as their ticket back to Earth. Before that mystery can be solved we get plenty of prison drama as Dredd tries to fit in and survive in a tough jail.
Toby Longworth still provides the best voice of Dredd there is, and there is a nice turn by Nicola Bryant as Judge Mordin. I didn't see what was coming with this adventure but it is another shortish Big Finish drama and doesn't quite meet the high standards of the Johnny Alpha story so 3 out of 5 legal Eagles for Trapped on Titan. Now for the latest Doctor Who release.