Dempsie will play DI Miles Southgate, while Annis will play a character called Dame Harriet Kenny.
Other high profile cast revealed today include Nina Toussaint-White (Bodyguard) and Fisayo Akinade (Heartstopper).
Watching new cast added is always one of the most rewarding elements of creating a show, said Richards.
Joe Dempsie and Francesca AnnisEric Frideen; courtesy
It is truly a privilege to have actors of such variety and talent.
But who is this unnamed Officer X?
The series will again explore public outrage and question what happens when a trial is dominated by contentious issues.
I was enamored by the scripts and left guessing until the final page.
