Cassie has been exploring the Quantum Realm Hope. When they test the device out, it accidentally sends her, Hope, Scott, Hank, and Janet into the Quantum Realm, where they face the dangerous Kang the Conquer, someone from Janet's past in the Quantum Realm. Meanwhile on Earth, Luis tries to figure out where Scott and Cassie have gone, since they've become like family to them. When he finds the device, he turns to someone who he knows is good at the science.
