Seventeen-year-old Eddie Savage is shocked to learn that the body of his brother, Steve, has just been washed up in the Thames. But he soon discovers something even more disturbing: that Steve had actually been working undercover for the police - and was probably murdered in the line of duty. Determined to avenge his brother's death, Eddie relinquishes his old life and identity to take up where Steve left off, throwing himself headlong into his first mission - to infiltrate a tough south London gang. But as he becomes caught up in the world of crime, Eddie begins to question where his loyalties lie. Then he makes a terrible discovery...