Michael Hollinghurst is a successful corporate lawyer living a comfortable, suburban life in leafy North West London. But on 7 July 2005, his life is transformed when he steps on a London underground train targeted by Islamist suicide bombers. While most passengers in his carriage are killed, Michael survives the explosion but is confined to a wheelchair as a result.
Coming to terms with his predicament and controlling his own feelings of guilt as a survivor conspire to push him in a direction that is out of character and a tad reckless. In a quest to seek retribution, he resorts to embracing the internet and posing as a radical Islamist in order to snare potential perpetrators.
Much to his surprise, his shambolic scheme yields results and is brought to the attention of both GCHQ and a terrorist cell. But before long, dark forces begin to gather and close in on him. There is seemingly no way out for Michael Hollinghurst. He has become, quite literally, a sitting target.