A bull Columbian mammoth slips through an anomaly, rampaging along the M25 scattering cars and lorries in its wake. As Cutter, Abby, Connor and Jenny take on the task of stopping it, Stephen is shocked when Helen returns with plans of her own. After taking the mammoth back to the ARC, Cutter decides to set a trap to root out the traitor in their midst, leaving Lester to fight for his life against a future predator that has infiltrated the ARC.
