The battle between the Winx and mummies continues as Selina summons the Sphinx to attack. Bloom spots Selina in the library, but just as she is about to ask what is going on, Selina sets the place on fire, and the fight heats up.
Selina awakens the Sphinx and unleashes it upon the whole city of Alexandria, causing the Winx to halt their search for the Fairy Godmother's diary.
After the Mummies are defeated, Selina summons the Sphinx, which begins to wreck havoc on Alexandria. The Winx are forced to deal with it and lead it away from the Lost Library and the tourists. While they are busy, Selina teleports to the Library of Alexandria to find Eldora's diary and destroy it because it is the only link to telling how to seal the Legendarium for good. Due to the fight with the Sphinx, the Library of Alexandria is about to get buried under rubble and become lost forever. Bloom heads back to Library of Alexandria to look for the diary before it also gets lost. The rest of the girls, after a harrowing fight, are given a chance by the Sphinx to stop it by solving its riddle with only three tries: "There are millions of books in the Lost Library. How many letters are there in those books?".
Meanwhile, Bloom uses her senses to find the diary, then is shocked at the appearance of Selina, who is revealed to be a childhood friend of hers. Selina uses that to fool Bloom and after that she insensibly causes the Library to collapse even more. This allows her to escape, while Bloom does not see her, although without Eldora's Diary.
Chatta impulsively shouts out a random large number, which probably is not even a real number, and wastes the first chance. Tecna uses a program to calculate the number and gives her rough estimates. To her shock, it is also wrong. With one try remaining, Chatta figures out the riddle; the first part of the riddle is a distraction to over-think it, and the answer is 10. There are ten letters in "those books". The Sphinx is shocked that his riddle is solved and screams in disbelief as it is once again sealed.
Bloom digs her way through the debris and falling rocks to the surface. Everyone congratulates Chatta on solving the riddle. Bloom then shows the diary that she found in the Library. After reading the diary, Winx decide to follow Eldora's path using the air balloons.
- The Winx defeated the Mummies.
- The Winx continue to find Eldora's diary.
- Selina summons the Sphinx to attack the city of Alexandria.
- Bloom and Selina are revealed to be childhood friends.
- Bloom finds Eldora's diary.
- Chatta solves the riddle of the Sphinx, defeating him.
- Winx Club
- Water Bolt - Used by Aisha against the Mummies.
- Light Spectrum - Used by Stella against the Mummies.
- Total Eclipse - Used by Stella to remove the Trix's spells affecting people.
- Chlorophyll Bolts - Used by Flora against the Sphinx.
- Lilac Vortex - Used by Flora against the Mummies.
- Infinite Echo - Used by Musa against the Mummies.
- Volcanic Attack - Used by Bloom twice, first against the Sphinx, then against the rocks.
- Chaotic Confusion - Used by Darcy against the tourists.
- Dome of the Ocean - Used by Daphne to defend Icy, Darcy and Stormy (in fairy disguise).
- Dance of Leaves - Used by Daphne against the Sphinx.
- Magic Chamomile - Used by Amore to calm the tourists.
- Flame Spiral - Used by Daphne against the Mummies.
- Winx Rising Up Together
- Pop Goes the Mummy
- Winx to the Top
- Bloomix the Power of the Dragon
- Living the Magic
- Due to the fact that the Winx (minus Bloom) originated from the Magic Dimension, they do not know much about the Sphinx statue.
- When Daphne attacks, she summons a particular element for power; e.g. "I call upon the power of Water! Dome of the Ocean".
- Interestingly, Daphne seems to know more about Ancient Egyptian culture than Bloom does. This might be because she is the teacher of Magical History at Alfea.
- Daphne casts a Convergence spell with the other Winx (minus Bloom) even though she has Sirenix powers while the Winx have Bloomix powers.
- In Italy, this episode was aired four days before the sixth episode and one week before the previous episode.
- This episode aired along with "The Lost Library" in the US.
- This episode is the last episode to be aired on Nick USA and Nick Jr USA will take over to air the rest of the Winx Club episodes for this season.
- The Sphinx is shown with its 'beard' both in its stone and magical form. The beard was broken off thousands of years ago.
- Some of the filler characters of Bloom's flashbacks to Earth are minor fairies at Alfea, instead of normal humans.
- In the scene that people are running from the Sphinx and before Piff shoots dream dust at it, Tecna shoots Musa's sonic beam at the Sphinx and Musa's shoots Stella's energy beam at the Sphinx.
- In one scene, we can see a part of Tecna's skull.
- In one scene, Musa's legs are transparent.
- Throughout the episode, Evy's eye color switches between sea green to brown.
“Well, you could say I have a way with words.”
“All these ancient civilization is just ranging in a word puzzle? What a joke!”
“Oh man! These mummies are all over the place!”
“Yoo-hoo, Mr. mummy!”
“I know, we got to stay alert. We're within wading distance.”
“We wouldn't miss this for the world.”