Supergirl #22

"Who murdered Krypton? Supergirl and Krypto rocket into space, en route to the Green Lantern world of Mogo, where she hopes to find clues about Rogol Zaar and his connection to the destruction of Krypton. Instead, she finds whispers and cover-ups. What are the GLs hiding? And will they go from Green to Red when they find out she's in possession of Zaar's weapon of war? (Hint: yes!)"