A returning war veteran with PTSD (played by Stephen Lang) takes to the streets of Boston with his military dog, and becomes trapped on the Tobin Memorial Bridge when a revolutionary uprising takes over the city. Suddenly, a gang of ruthless ex-military terrorists, led by an enigmatic commander (Chiwetel Ejiofor), seize control of the bridge and take everyone hostage. The veteran now has only his military dog by his side as he attempts to save his own life and that of his teenage sister (Alice Eve) and the rest of the hostages.