Part 2 of a 3-part time-travel adventure brings the Rats' face-to-face with Superman! The Lab Rats begin to piece together what caused Superman to disappear from Metropolis some fifty years earlier. But will they be able to determine how his absence caused the city's downfall? And will a new, even greater danger, one that threatens all the Earth, make it a moot point?

Notes:

• The cover is a homage to the cover of Baffling Mysteries #7.