The Cage is a training section in the Providence Basic Training facility. Providence Basic cadets go to the Cage in order to build their combat abilities while facing off against a variety of EVOs. For safety purposes, the EVOs are equipped with special collars that restrict them from using their full power.
Believing Rex's powers would give him an unfair advantage in the Cage, Kenwyn Jones deactivated the EVOs' collars. However, Kenwyn was sent in instead and was left unable to defend herself. The EVOs broke out and raided all of Providence Basic Training until they were captured by Noah, Rex, Kenwyn, and another male Providence cadet.