In England in 1963, Nicholas Elliott works for MI6 but is left in turmoil when he learns his close friend and colleague Kim Philby had been secretly working as a double agent for the KGB and has defected to the Soviet Union.

A Spy Among Friends follows the defection of notorious British intelligence officer and KGB double agent, Kim Philby, played by Mare of Easttown's Pearce, through the lens of his complex relationship with MI6 colleague and close friend, Nicholas Elliott (Lewis).

In England in 1963, Nicholas Elliott (Lewis) works for MI6 as an intelligence officer but is left in turmoil when he learns his close friend and colleague Kim Philby (Pearce) had been secretly working as a double agent for the KGB and has defected to the Soviet Union.—wikipedia