Following the two-episode premiere, the remaining six episodes will be released weekly, with Season 1 of the show telling the story of the first Percy Jackson novel, The Lightning Thief.
Warning: The rest of this article contains spoilers for Percy Jackson and the Olympians on Disney+, as well as for The Lightning Thief by Rick Riordan.
Percy's Quest to Hades Explained
Episode 2 of Percy Jackson and the Olympians sees the titular hero be assigned his first quest — to retrieve Zeus' stolen Master Bolt (the god's symbol of authority) to prevent a major war among the gods of Olympus.
Though not entirely certain, Chiron (Glynn Turman) and Dionysus (Jason Mantzoukas) are fairly positive that Hades, the ruler of the Underworld, is the thief. They explain to Percy Jackson (Walker Scobell) that he would have had the motivation to do it, given his known resentment toward his brothers Zeus and Poseidon.
Meanwhile, many, including seemingly Zeus, believe the theft was Poseidon's doing and Percy himself stole the bolt on his godly parent's orders. Believing this, Zeus gives Poseidon until the summer solstice (one week from the events of the second episode) to return the Master Bolt, and if he fails to do so, he will wage war.
Mr. D (which is what Dionysus is called at Camp Half-Blood) tells Percy this point blank. When Percy asks who stole the Master Bolt, Mr. D responds by simply saying, "You did." He says that a forbidden child of the Big Three (forbidden as the three gods made a pact not to father more demigod children) being claimed, right as the deadline approaches may be seen as evidence of Zeus' suspicions toward the sea god.
To both prove his — and his father's — innocence, and on a greater scale, to prevent a potential war among the gods, Percy must retrieve the Master Bolt from Hades, the supposed thief, and return it to Zeus before the deadline. A minor change, but The Lightning Thief novel gives Percy 10 days to retrieve it, while the show only gives him seven.
Another interesting difference is Percy is told all of this before even agreeing to the quest in the show, whereas Chiron made him agree before telling him all the details in the book.
He does this because to get the bolt from Hades, Percy must travel to the Underworld — book-Chiron feared Percy would not take the quest if he knew that was where he was headed. The Disney+ adaptation proves him right, as Percy immediately declines, and continues saying, "No" throughout Chiron's explanation.
He only agrees after learning from Grover Underwood (Aryan Simhadri) that his seemingly dead mother may still be alive and that if he goes to the Underworld, he could theoretically bring her back.
This highlights another change from the books in the show. While in both versions Percy's true motivation and reason for saying yes to the quest is to bring back his mother, he does not let it show at all in the book.
He seems to be nodding along to the arguments that Disney+ Percy outright rejects, but, as he puts it in the novel, "All I cared about was my mom. Hades had taken her unfairly, and Hades was going to give her back."
In the show, though, Percy only agrees to the quest when he learns that he could get his mother back if he went to the Underworld.
Why Couldn't Grover Tell Percy Sally Might Be Alive?
Grover telling Percy about his mother possibly still being alive is not the first time the Satyr discussed it. He not only brings his suspicion that Sally may still be alive (despite it looking like the Minotaur killed her) to the Council of Cloven Elders but then relays what he learned to Chiron and Mr. D.
However, they tell Grover to not tell Percy anything, much to his dismay — he wants to be finished lying to his best friend now that he knows about Camp Half-Blood and his status as a demigod.
They warn Grover that "powerful forces are at work here ... forces that have laid waste to the Earth before and are close to doing it again," saying that keeping this a secret from Percy is extremely important.
Grover tells him anyway, though, despite even in the moment hearing Chiron and Mr. D try to get him to stop talking.
There is no actual book precedence for this specific secret needing to be kept, as it was not discussed at all, outside of Percy's inner monologue and the vague questions he asks about the Underworld.
But, there is certainly precedence for important information being kept from Percy — notably, The Great Prophecy, detailing a child of the Big Three's involvement in either the salvation or ruin of Olympus. Percy does not learn most of the contents of the prophecy until the fifth book in the series, repeatedly being told it was important he not know what he did not have to learn.
Even if not directly related to the Great Prophecy itself, the intended secrecy at least sets that precedence of Percy actively being withheld information, which becomes extremely relevant as the plot continues — in Season 1 and any potential continuation moving forward.
The first two episodes of Percy Jackson and the Olympians will hit Disney+ and Hulu sometime on December 19.