Apate tricked Ariadne in giving her magical String (the string used to help Theseus in the Labyrinth) for her own selfish reasons (which she wasn't able to do so). However, Apate lost the String shortly after her trickery after having an affair with a mortal man. The String dropped inside an open manhole, which rolled off to the Mines of Paris, got washed away by the sewer system and had gone missing ever since. Ariadne asks Sealtiel, a son of Apate, and some of his demigod friends to find the String as a peace offering to his mother. Once found, they will return the String back to Ariadne at the base of the Eiffel Tower.
Locations and Info:
- Camp Half-Blood Entrance: The questors will gather here before they depart for the airport.
- New York City Airport: The questors will take a ride on one of the airplanes to get to Paris; however, four nearby scythian dracanae are attracted to the demigods' scent, leading to a fight before they enter the airport's premises.
- Charles de Gaulle Airport: As they get out of the airport, they ask questions on who runs the Mines of Paris. One of the French people they asked directs them to go to the Paris Sewer Museum. They then go there by taxi.
- Paris Sewer Museum: When they arrive at the museum, they ask questions on how to get to the Mines. One of them, who happens to be a cataphile, tells them that those who explore the Mines illegally were confiscated of their possessions, including maps. Taking the risk, they decided to steal a confiscated cataphile's map from the museum's office to find an entryway into the Mines. They will discover and decide on three forbidden but accessible entryways. They will split up into two groups to explore the first two entryways at midnight.
- Entryway 1 (Two members): The manhole, which is located near the Pantheon in the 5th arrondissement, will be entryway # 1. When they reach the bottom and discover a dead end, they will discover an abandoned workshop. They then discover that it was a workshop of a BC son of Hephaetus through blueprints. Along with that, they discover that the son of Hephaestus attempted to turn the Mines of Paris into a labyrinth similar to Daedalus' original one to hide a very dangerous automaton he had attempted on completing: the Minotaur X (he made it to attack the Camp in the future); however, the automaton began to go haywire, and decided to shut it down. From then on, he abandoned the workshop out of frustration. He hid the automaton minotaur somewhere deep within the Mines to prevent others from getting to it. The blueprints didn't tell where the exact location was, only that it was hidden somewhere. The two members will then take the blueprints and head back.
- Entryway 2 (Three members): The manhole, which is located near the entrance of Paris' Chinatown in the 13th arrondissement will be entryway # 2. When they reach the bottom, they will discover a dead end after exploring the tunnels for some time. They will then discover a short, shimmering piece of the String, which got cut off from the rest of the ball after being caught in a hook submerged in the sewer water. The magic of the String will begin work, acting like a compass by pointing the other tip to show the direction where the rest of the String went. They then head back to meet the others.
- Pont Neuf: The questors will meet at this bridge and show their findings. When they compare the map and the direction the string is pointing to, they discover that the string is pointing towards the third entryway, which is located somewhere within Bois de Vincennes, the largest park in Paris, at the eastern edge of the city.
- Bois de Vincennes / Entryway 3: They will take a taxi ride for Bois de Vincennes. By following the direction the piece of the String is pointing to, they find the third entryway near the Temple of Love. But before they even open the manhole cover, a three stymphalian birds will notice and attack them. Once they defeat it, Apate appears. She tells them that she will help them in finding the String out of, surprisingly, pity on her son, Tiel, for carrying her burden. She gives them each a pair of magical glasses that can see through the contraptions and traps made by the child of Hephaestus. She then opens the manhole cover for them and leaves. They enter the manhole and climb down.
- Paris Mines Part 1 - The Sewer: As they climb down, they have to walk through a knee-high river of sewer water to reach upper ground, where they avoid several pit fall traps and an automated noose. When they pass through the traps, they have to crawl on small hole, where they slide down into a cavern with two forks.
- Paris Mines Part 2 - The Ossuary: When they get out of the tunnel, they enter an abandoned ossuary. They accidentally trigger a trap, leading to a fight between them and automaton skeletons. They follow the path of the ossuary, and crawl into a hole again.
- Paris Mines Part 3 - The Labyrinth: When they exit the ossuary, they find themselves in a place similar to the Labyrinth itself in which according to the blueprints of the son of Hephaestus, was the part where he successfully changed the Mines into a maze. Despite being guided by the string, they encounter more traps, holes, a few one-monster groups, turning points, landings and sewer passages.
- Paris Mines Part 4 - The Stairs: Upon exiting the labyrinth, they encounter a staircase spiralling deep into the ground. The bottom cannot be seen due to the darkness all over. As they go down, they trigger accidentally trigger a trap, causing the stairs to be blown off by bombs. The were not able to reach the top, and falls down.
- Paris Mines Part 5 - Minotaur X: Upon landing onto the rubble of the once stairs below, they discover a large cavern at the far end and from there, they hear a mechanical and wild sound. The automaton minotaur has awakened, and they have to defeat it.
- Paris Mines Part 6 - The Exit: When they defeat the Minotaur X, they look around the cavern to search for a hidden exit. Luckily, they find the secret escape route created by the child of Hephaestus, and they escape the cavern. Upon reaching the top, they enter a long sewer, and on a hook by the sewer floated the object they were looking for: the String. They retrieve it and walks down the sewer passageway to find an exit. They find a ladder towards an open manhole and they climb out of it. They then find out that they have reached the Bois de Boulogne, which is at the other side of the Bois de Vincennes.
- Eiffel Tower: They they take a taxi for the Eiffel Tower, after changing clothes. Upon arriving, they meet Ariadne at the base and gives her the String back. After that, they retrace their steps back to Camp Half-Blood. But before they leave Paris, they take a break at a hotel and leave the day after.
- Endgame follows.
On the way back to Camp, they are unknowingly pursued by a Braxas, drawn by Skylar's power. The Braxas envelops Skylar and runs off away from them. This will stem into another quest, in which a new bunch of demigods must save Skylar before she causes trouble and before its too late for her.