While a deadly hacker turns Britain upside down, Danny decides weather to reveal all to Will, MI5 hunts the source down to an Islamic mosque with the help of Mi5's best computer programmers. But things get suspicious when Ruth, close onto the tail of the hacker, goes missing and so does a member of the special team...
Elenco: Peter Firth , Nicola Walker , Matthew Macfadyen , Richard Armitage , Keeley Hawes , Hermione Norris , David Oyelowo , Max Brown , Lara Pulver , William Hope , Anna Chancellor , Sophia Myles , Natasha Little , Richard Harrington , Shauna Macdonald , Gemma Jones , Alex Lanipekun .