During a meteor shower in Midvale, Supergirl notices a Kryptonite meteor. Determined to find an antidote to Kryptonite, she coats the meteorite in lead and then recovers it. She then uses a small chemical laboratory in the orphanage to do experiements on the Kryptonite. Unsuccessful, she discards the modified Kryptonite, now known as X-Kryptonite.
Soon after, she rescues a cat from a bullying dog. The cat follows her back to the orphanage, where he becomes exposed to the X-Kryptonite. This gives him super powers similar to that of a Kryptonian. The cape from a Superman doll falls onto the cat after he smashes the doll, making him Streaky the Supercat.
Streaky then performs a series of super feats, until Supergirl takes notice. She then romps with the cat in outer space, until his super powers wear off and he begins to fall. She quickly saves the now depowered cat.
- Supergirl seems to have a need to "romp" with other Superbeings. She previously did this with Krypto in "Supergirl's Farewell to Earth", and with Superboy in "Superboy Meets Supergirl!".
- This story marks the first appearance of Streaky. His next appearance would come in "The World's Mightiest Cat!".