Robert Kanigher and Jon Chester Kozlak bring Neptune Perkins back in Flash Comics 81 (March 1947).
The story reveals that Neptune Perkins now has a brand new houseboat. Both Perkins and Hawkman receive a telepathic summons, which leads them to a giant lightbulb. This is really a spaceship, which takes them both to Venus.
The Venusians have brought the two to their planet for help against two monsters, who resemble the Roc and Kraken from mythology. Hawkman and Neptune each fight the creature from their respective environments, and then return to Earth.
Though Neptune Perkins does not appear again in the Golden Age, he does return in All-Star Squadron in the 80s.