A student from Lebanon is out to kill the man who shot down her three brothers in cold blood. The Irish widow of a Hizbollah fighter, now resident in London with her student son, plans a vicious revenge for her mother's death. While an al Qaeda-affiliated terrorist is masterminding the murder of innocents on an horrific scale, his suicide bombers will board four trains out of London and, simultaneously, blow all four apart. Matt Locksley from MI6 must discover their plan before it is too late. But his progress is dangerously slow as the time for the killings draws near. Many lives are at stake and he has only a few hours in which to save them...