Four Muslim youths living in the UK: Omar (Riz Ahmed), white Barry (Nigel Lindsay), Wai and Faisal are using a toy gun as a prop to shoot a jihad video. Dedicating themselves to jihad is their fanatical dream. Omar is tired of Barry's nonsensical theory of eating phone cards to avoid being tracked, and he and Wai go to a Muslim guerrilla fighter training camp in Pakistan to study. Omar and Wai's hard training life soon ends because they accidentally hit their comrades; Barry, who stayed in the UK, looked for comrades and found Hassan, an Arab youth who questioned British current affairs in public. Together with Faisal, who used voice-changing techniques to collect peroxide to make bombs, they developed bombs. Omar, who returned home, lied that he had received a task to make bombs and put others under his control. Faisal was killed in the bombing due to a mistake, and the remaining four Muslim fighters set their sights on the London Marathon...