A pinch of Fairy Dust will do it!
The Winx go to Andros, the planet of Aisha, to participate in the festival of the kingdom. Meanwhile, Obscurum and the Staryummies attack Gorgol, the underwater star of Andros. The Winx, aided by Nex, are transformed into Sirenix fairies, ready for a new submarine mission, but discover that Obscurum and the Staryummies have already stolen the light of Gorgol.
- The Winx and Nex arrived on Andros to celebrate the kingdom's anniversary celebration.
- Valtor sends a predator creature to the underwater realm of Andros while Obscurum attacks the Core of Gorgol.
- Ligea and Dorana creates a barrier around Gorgol but failed due to Obscurum and the Staryummies already attacking Gorgol.
- The Winx transform into Sirenix fairies and, along with Nex, swims towards to the underwater star, Gorgol.
- The Winx face a mutant shark under Valtor's spell while Nex fight against Obscurum.
- After trapping the mutant shark, the Winx tries to prevent the Staryummies from stealing the light of Gorgol's core. Meanwhile, Obscurum launches a surprise attack by trapping Nex with an upcoming collapsing rubble.
- Neptune's Sting - Used by Aisha against the mutant shark.
- Logic Net - Used by Tecna to defend Bloom and Aisha.
- Blinding Ray - Used by Stella against the mutant shark.
- Morphix - Used by Aisha against the mutant shark's tail.
- Morphix Barricade - Used by Aisha to defend Nex.
- Morphix Punch - Used by Aisha against Obscurum.
- The episode title in the English dub was originally titled as "Into the Depths on Andros".
- In the Italian dub, the transformation phrase "Magic Winx, Sirenix" was used, but in the English and other international dubs, "Winx Sirenix" was used.
- In the English dub, Sirenix is pronounced as both "Sirenix" and "Syrenix" throughout the episode with the latter being the Italian's version of the pronunciation.
- It is revealed that the Winx can transform back to any transformation they have earned throughout the series as seen with the case of Sirenix.
- This also marks the return of Sirenix since "[[Winx Club - Episode 603|The Flying School]" for Stella, Flora, Aisha, Tecna, and Musa and "The Golden Auditorium" for Bloom respectively.
- The monster form of the shark transformed by Valtor looks very similar to the Kaiju Slattern from the movie Pacific Rim and might have been inspired by it.
- Obscurum mentions about attacking the star of Callisto, a planet which had not been mentioned since Season 1.
- The cave where the Winx trap the mutant shark in is similar to the cave where the Beast of the Depths resides in.