- "No finding girl. Fortress bad. Many weapons. No way out. No way in."
- —Jo Gunraf to Supergirl and Mon-El[src]
After Supergirl took down Roulette's illegal alien fight club, Roulette was told by one of her fighters about Slaver's Moon and offered her services to the Maaldorians to expand their slaver market to Earth. She and her associates began abducting humans, including Izzy Williams, from Earth and kept them in a cell inside the Red Fortress. Izzy's mother came to CatCo seeking answers about her daughter's disappearance so Kara and Mon-El investigated the disappearances and wound up on Slaver's Moon. They surrendered themselves and were put into the fortress prison. After a Dominator purchased the humans, Supergirl inspired the other human captives to fight back and they were able to overpower the Maaldorian guards and escape the fortress.