The multi-award winning drama, 'Silent Witness', returns for Series 21. Dr. Nikki Alexander (Emilia Fox), Jack Hodgson (David Caves), Dr. Thomas Chamberlain (Richard Lintern) and Clarissa Mullery (Liz Carr) form a committed team of forensic pathologists and scientists, trying to figure out how and why the victim died. Nikki and Jack are affected from the fallout after Mexico, while there's a cuckoo in the nest. A series of tragic events are linked to a cyber hacking. A US Diplomat is shot dead in Central London. Care home abuse is uncovered after a road traffic accident. Festive celebrations are interrupted by the aftermath of a shooting spree at a family house.