En Crisis Zone tomamos el papel de Croad MacGalain, un oficial de las Fuerzas Especiales Tácticas que debe de salvar el complejo de Garland Square, en pleno centro de Londres, del grupo terrorista que lo ha tomado. Garland está compuesta por un edificio de oficinas, un parque, un centro comercial y un hotel, donde los terroristas han secuestrado a todos los presentes. Como siempre, llega la hora de salvar los muebles enfrentándonos a un auténtico ejército de enemigos...
Garland Square recently opened on the outskirts of London. This urban complex contains hotels, a mall, a park, and an office complex. Unfortunately, the entire facility has been overrun by a terrorist organization known as the U.R.D.A., headed by Derrick Lynch. The terrorists have made no demands, neither they have any motives. Facing an unknown threat, the government thus concludes that the U.R.D.A. must be stopped at all costs and Lynch must not be allowed to execute his hidden agenda, whatever it may be. With the aforementioned in mind, the Special Tactical Force has been ordered to liberate Garland Square and suppress the U.R.D.A. Squad 1, the task force responsible for the liberation of Garland Square, is led by Claude McGarren.
Although heavy resistance was imminent throughout the complex, Squad 1 secured the area although Lynch was not visible. STF Headquarters than receives disturbing information about Lynch's goal of "over-working" an experimental atomic reactor 5km below the complex. McGarren and Squad 1 engaged in a tense time-sensitive conflict to nullify Lynch and to prevent the reactor from becoming unstable, ultimately saving the security of London.
Six months after the Garland Square incident, new U.R.D.A. mastermind Jared Hunter hijacks Grassmarket District and as an insurance policy, has Melissa Kessler (the S.T.F. Commander's daughter) in custody. Although Hunter's demands include but not limited to the release of his comrades in exchange for the complex's freedom, he is seeking revenge against the S.T.F. platoon (Squad 1) for ruining the organization's plan of attack at Garland Square.