What Lies Beneath.Rex receives an unexpected phone call from Circe, who claims that there is a problem in Abysus. Rex, Six, Holiday, and Bobo travel to Abysus and find the landscape wasting away, and encounter Circe and the Pack, who explain that Van Kleiss's death has caused the nanite-infused environment of Abysus to come undone. They claim that the only way to reverse the process is via a machine built by Van Kleiss, and Rex reluctantly agrees to help them after Dr. Holiday mentions the risks of allowing the corruption of Abysus to continue. However, Rex backs out after discovering that the machine is designed to resurrect Van Kleiss. The room then floods with nanite ink that begins to drown everyone, forcing Rex to activate the machine and bring back Van Kleiss, who refuses to save Rex's friends until he promises to join him. Rex agrees, and Van Kleiss releases the others. Rex reluctantly shakes Van Kleiss's hand, but realizing that Van Kleiss's new nanites have been altered, he successful cures him. Van Kleiss and the Pack then escape via Breach, and Circe leaves after telling Rex that she can't abandon Van Kleiss.