While the Winx save Sky from the frozen lake, Icy meets the white fox: it turns out that Dyamond is the planet of the witch and that the fox is actually her sister Sapphire, transformed into an animal by a shaman witch that years before she arrived on Dyamond and froze everything. Since then, Icy has vowed to become a witch stronger than her and to break the spell. The white fox accompanies the Trix in the subsoil of Dyamond by the prime star, which however ends up in a tunnel, in which Sapphire slips to retrieve it. In an attempt to enlarge the opening with magic, Stormy causes a collapse of the vault, forcing the witches to escape and abandon the primary star; the latter, however, appreciating that Icy has rescued Sapphire instead of abandoning her to danger, hands herself over to the witch. Icy uses the star's power to free herself and the other Trix from Valtor's mark, but the star isn't powerful enough to bring Sapphire back to human, if not for a few moments. Returning to Alfea, the Winx, still having all their stars despite having three out of seven, arrive at the conclusion that the last prime star is the exclusive property of Icy, and therefore they are still tied with Valtor.