Re-cap on the series

Percy Jackson is a twelve year old boy with dyslexia and ADHD (Attention Deficit Hyperactivity Disorder). After going on a field trip and being attacked by his pre algebra teacher, who is actually a Fury in disguise, he finds out that he is the son of a Greek god. He is brought to Camp Half-Blood (a camp for children with a Greek god as a parent, located off Long Island) by his best friend, a satyr named Grover, and his mother Sally. He soon meets Annabeth, daughter of Athena, and they quickly become good friends. Not long after his arrival, Poseidon, the sea god, claims Percy as his son during a game of demigod-style capture-the-flag. Percy is accused of stealing Zeus' masterbolt, the model for every lightning bolt made. He, Annabeth and Grover are given ten days to return the thunderbolt to Mount Olympus in order to stop a war between the gods from starting and save his mother, who has been held hostage in the Underworld by Hades after being captured by the Minotaur. He soon finds out that Hades did not steal the bolt. It is revealed that Luke, son of Hermes, stole the bolt for Kronos, who is attempting to come back to life. Grover goes off to find Pan, the lost Greek God of nature.

In the second book, the shortest novel of the series, Percy's empathy link between Grover and himself kicks in when he has a dream which is the reality of Grover. Grover has been kidnapped and taken to an island in the Sea of Monsters, known to humans as the Bermuda Triangle, a dangerous sea that is almost impossible to pass through and get out alive. Thalia's tree (responsible for keeping Camp Half-Blood safe) is poisoned. Percy, Annabeth, and his new half-brother Tyson the Cyclops go and try to not only save Grover, but also to retrieve the Golden Fleece. The Fleece is the only thing that can stop Thalia's Tree from dying, which would leave Camp Half-Blood vulnerable to an attack by the Titans and Luke. In the end Thalia's Tree is not the only one healed, Thalia is also brought back to life.

Grover the satyr has gone undercover to a school in search for half-bloods, and finds two powerful siblings, Nico and Bianca di Angelo. While on this mission, they are attacked by a manticore, but are saved by the Hunters of Artemis, who arrive just in time to help. Annabeth falls off a cliff in an attempt to kill the manticore, and Percy soon learns that somehow she survived and has been captured by Luke. Bianca joins the Hunters and Nico leaves camp. Soon after arriving at camp, Percy learns that Artemis herself has been captured, too.

Percy, Grover, Thalia, Bianca, and Zoë Nightshade (Artemis' lieutenant) go on a quest to rescue them. They learn that Atlas, a powerful Titan has escaped his torment (holding up the sky) at the Mountain of Despair on California's Mount Tamalpais, and is intent on stopping the heroes from success. They defeat him, but not before losing both Hunters in the quest. At the solstice, Thalia replaces Zoë as Artemis' lieutenant. As soon as they return, Nico is told about Bianca's death. He blames Percy, accusing him of failing to protect her like he had promised. When a few undead skeletons appear, Nico thinks that Percy is now trying to kill him as well. He looks at them and they are banished to the Underworld, and runs away. Percy realizes that Hades is Nico's father. At first Percy, Annabeth and Grover think that this goes against the promise of the Big Three, which is to never have demigod children, but then they realize that the two siblings had been in the Lotus Casino (a casino where time is nonexistent) since before the pact was made.

After being attacked by monster cheerleaders at his new school, Percy returns to Camp Half-Blood and learns about "The Labyrinth", part of the palace of King Minos in Crete that, according to Greek mythology, was designed by Daedalus. During a game/battle with giant scorpions, Annabeth and Percy find an entrance into the Labyrinth. Percy soon learns that Luke had used the entrance and will lead his army through the Labyrinth straight into the heart of camp. Annabeth also finds out that she is going to lead a quest for the first time in her life. To get into the Labyrinth, Percy has to find a blue Delta Symbol (Δ) (representing Daedalus) on a passageway, touch it, and then enter the Labyrinth to find Daedalus. Then Percy, Annabeth, Grover, and Tyson learn that the Labyrinth is known to grow on its own, and cause madness that could lead to death. While in the Labyrinth, they (with Nico) discover Pan, and he speaks words of wisdom to all of them. When he dies, part of his essence enters each of the characters except Nico. Percy later notices that Pan did not even speak to Nico.

Using the Labyrinth, Percy tries to find Daedalus so Luke cannot get Ariadne's string, (a string that can help anyone travel through the Labyrinth without getting lost), thereby foiling Luke's invasion. He gets the help he needs from a mortal girl named Rachel Elizabeth Dare, who can also see a path in the Labyrinth leading to Daedalus. Kronos finds out that Nico di Angelo is a son of Hades and also could be the child of the prophecy. Luke reaches Daedalus and gets Ariadne's string which he uses to lead his army to attack Camp Half-Blood. Grover comes to the rescue and causes a Panic (a scream that symbolizes the wild god Pan) to scare away the enemy. After the battle, Daedalus sacrifices himself to close the Labyrinth, which is tied to his life.

Percy Jackson and his friends fight in a war resembling the original war between the Greek gods and the Titans and in a final battle with the powerful Titan, Lord Kronos. Seeking to defeat Kronos, Percy baths in the River Styx, like Luke, to make his body invulnerable except in one spot (mortal point; in Percy's case, the small of his back). Percy and his friends then fight in a last stand to protect Mount Olympus from the oncoming invasion of Kronos. Percy finds out the last Olympian is Hestia and gives her Pandora´s jar, telling her she is the last and most important Olympian "because hope survives best at the hearth". Percy and Luke (possessed by Kronos) battle at the top of Mt. Olympus. Luke is shocked back into his normal self and commits suicide to destroy Kronos and save Mt. Olympus. The gods reward Percy and his friends and grant him one request. He requests the gods to recognize all their children and make a place at Camp Half-Blood for Hades and all the children of the minor gods.