Valtor decides to attack the star Hypsos, which is located in the star's constellation of the Hydra. When they discover that Hypsos is in danger, the Winx set off on a new mission to save the star. When they arrive on Hypsos, Valtor then uses his powers to turn the constellation of the Hydra into the actual Hydra monster. While the Winx face the Hydra, Musa saves Riven and the two seem to draw closer. The Specialists come to aid the Winx in fighting the Hydra, but it seems nothing affects it. None of the attacks of the Specialists nor the Winx do any damage to the monster. Obscurum opens a giant dark portal for the staryummies to go through, and Bloom comes with an idea to trap the Hydra in the dark portal. The Winx use their Cosmix Power Supernova spell to push the Hydra into the portal, and they successfully defeat it. The monster then transforms back into its original constellation of stars form, and Hypsos is saved. The Winx goes back to Alfea and hold a concert, but during the concert, Riven tries to impress Musa by making one of the projectors near the stage show Musa in the sky above the stage in different poses. Musa doesn't like what Riven did, and leaves the stage at once.