The Winx return to Alfea and discuss with Ms. Faragonda about the new threat, Tritannus and about their Believix powers being less effective underwater. Faragonda tells them they will need to acquire Sirenix, an ancient power and that the last fairy to acquire the power was Bloom's sister, Daphne and Daphne knows where the find the Book of Sirenix. Bloom meets with her sister, who warns her to not seek the power and that it is also what caused her seemingly to die, but Daphne tells Bloom the Book of Sirenix is located in the Magic Archives of Alfea. The Winx along with Sky, Brandon, Helia and Princess Krystal, who is the princess of Flora's realm, Linphea. The Trix attack the Winx with their new powers thanks to Tritannus. During the battle, Sky takes a blow to the head that causes him to lose his memory.