Dredd is based on the popular British comic book character created by writer John Wagner and artist Carlos Ezquerra that first appeared in 2000 A.D. #2 (March 1977). The screenplay was written by Alex Garland (28 Days Later). Here's a partial synopsis:
During a routine day on the job, Dredd (Karl Urban) is assigned to train and evaluate Cassandra Anderson (Olivia Thirlby), a rookie with powerful psychic abilities thanks to a genetic mutation. A heinous crime calls them to a neighborhood where fellow Judges rarely dare to venture — a 200-story vertical slum controlled by prostitute turned drug lord Ma-Ma (Lena Heady) and her ruthless clan. When they capture one of the clan’s inner circle, Ma-Ma overtakes the compound’s control center and wages a dirty, vicious war against the Judges that proves she will stop at nothing to protect her empire. With the body count climbing and no way out, Dredd and Anderson must confront the odds and engage in the relentless battle for their survival.
Dredd was produced by Academy Award-winning director Danny Boyle's (Slumdog Millionaire) DNA Films. It was written by Alex Garland (28 Days Later). The cast includes Olivia Thirlby as Judge Cassandra Anderson, Langley Kirkwood as Judge Lex and Deobia Oparei as Judge T.J. Alvarez and Lena Heady as Ma-Ma.