Zgodba o ženski, ki je zavoljo svojega sina prisiljena izdati vse, v kar verjame. Collette McVeigh je samska mati, ki se je za svojo otroško napako spokorila tako, da je postala radikalna aktivistka Irske republikanske armade. Ko jo aretirajo zaradi sodelovanja pri spodletelem bombnem napadu v Londonu, jo tajni agent MI5 postavi pred izbiro: ali gre za petindvajset let v zapor in izgubi sina ali pa se vrne v Belfast in začne ovajati svojo družino. V skrbi za sinovo prihodnost se Collette s težkim srcem vrne domov in postane vohunka britanske obveščevalne službe…
In 1993, the IRA member Collette is arrested in the London tube after leaving a bomb in the facility. MI-5 Agent Mac offers a deal to Collette to become an informer. She accepts the agreement to protect her son and in return Mac offers a new identity to her after a period working for the MI-5. Soon Mac learns that his superior Kate Fletcher is using Collette to protect her mole inside the Irish organization. Mac tries to find the identity of the informer and protect Collette.