The Beast Must Die (DVD)

After the investigation into the fatal hit-and-run of her young son is dropped, Frances Cairnes (Cush Jumbo) takes matters into her own hands, plotting to kill George Rattery (Jared Harris), the pompous man she suspects is responsible. Troubled detective Nigel Strangeways (Billy Howle) ends up working both to prove George's guilt and head off Frances's plans for revenge.