The final installment of Rick Riordan’s Trials of Apollo pentalogy, The Tower of Nero (2020) is a young-adult fantasy book set in the Percy Jackson universe. The novel tracks the fallen god Apollo in his final quest to save the world from the cruel emperor Nero and the monster Python. Apollo’s dangerous adventure quest takes him, with his demigod companion Meg McCaffrey in tow, to underground tunnels, a sinister Manhattan high-rise, and the deathly lair of a malicious ancient serpent. Apollo and Meg defeat old and new enemies to transform into their better selves, an important theme in the novel. Praised by readers for providing a satisfying close to the Trials of Apollo series, The Tower of Nero won the Goodreads Choice Awards 2020 for middle-grade and children’s fiction.

The plot of the novel begins immediately after the events of The Tyrant’s Tomb, the fourth book of the series. After finally defeating Caligula and Commodus at New Rome, a sanctuary and university for demigods in San Francisco, Apollo and Meg receive a prophecy that directs them to seek Nero out in Manhattan.

The author of more than 20 New York Times bestselling books for young readers, Rick Riordan taught Greek mythology for several years before turning to full-time writing. Riordan’s writing often places elements from various mythologies in a contemporary context.

This guide refers to the 2020 Puffin Books UK edition.

Content Warning: This guide discusses the novel’s themes of emotional abuse and manipulation.

Plot Summary

Following the events of The Tyrant’s Tomb, the prequel to The Tower of Nero, Apollo, in the form of human teenager Lester Papadopoulos, and his companion Meg McCaffrey, head to New York city by train to find and defeat the evil emperor Nero. A two-headed snake dressed as a man enters the train car and prophesizes that Apollo and Meg must seek help from the son of Hades and his cave-dwelling friends. The snake-man is killed by Luguselwa or Lu, an associate of Nero’s who seems to have arrived to capture Apollo and Meg. However, Lu is on Meg and Apollo’s side. She helps them escape the train, which is crawling with Nero’s soldiers. Lu devises a strategy to take down Nero: Apollo must pretend to kill her so Nero does not suspect her loyalties. Once Nero takes back Lu, Apollo and Meg can surrender to him. Inside the Tower of Nero—Nero’s lair—Lu will help Apollo destroy Nero’s fasces, the axe that holds his life force and an important symbol throughout the novel.

Apollo stages the murder attempt by throwing Lu off a roof in view of Nero’s surveillance cameras. He receives another bit of prophecy that leads him and Meg to Camp Half-Blood, the training school for demigods, children of mortals and gods. Meg too is a demigod, the daughter of a human botanist and Demeter, the goddess of agriculture. Nero, Meg’s adoptive father, raised her as a weapon since she was five years of age. Meg has fled Nero’s abuse to ally with Apollo. At Camp Half-Blood, the duo catches up with Apollo’s demigod children and their friends, including Nico di Angelo, a son of Hades, the god of the underworld. Recognizing that Nico may have a part to play in the quest, as the snake’s prophecy suggested, Apollo agrees to take him and Will, Apollo’s son, to New York.

In New York, the group visits Rachel Elizabeth Dare, the priestess of the Oracle of Delphi. Rachel receives a prophecy that Apollo’s ultimate fight will be with Python, the primordial serpent who has seized Delphi. To take down Python, Apollo himself will have to fall. Rachel shows the group the floor plans of Nero’s tower and tells them the emperor is hoarding massive stocks of Greek fire, a highly combustible liquid, in his underground chambers to burn down New York. While Apollo and Meg surrender to Nero, the rest must find a way to disable the vats of Greek fire. Nico takes the group to the tower via an underground way so that they escape Nero’s surveillance systems. En route, the group meets troglodytes or trogs, a subterranean humanoid people whom Nico befriended during his many trips to Hades, the underworld. Apollo persuades the trogs to help the group by destroying the Greek fire. The trogs tunnel Apollo and Meg close to Nero’s tower and start burrowing a way into the Greek-fire vats.

Apollo and Meg surrender themselves to Nero, but their plan backfires when Nero reveals he knew of Lu’s deception all along. The emperor has Lu’s hands cut off as punishment. He dispatches Apollo and Lu into a holding cell and takes away Meg, his adopted daughter. Nero plans to use the Greek fire in less than eight hours. Apollo deploys his healing powers to relieve Lu’s pain and cauterize her wounds. Lu suggests Apollo use his powers of prophecy, an important motif, for guidance on next steps. In a dream-vision, Apollo discovers Nero’s fasces is being held in a room on the same level as the holding cell and is protected by a leonotocephaline, a man with a lion’s head, his body encircled by a headless snake. The guardian can let go of the fasces if he is offered immortality. Apollo and Lu ambush a guard and escape their cell. Lu plans to trade her immortality to the guardian in exchange for the fasces.

Apollo goes off to seek Meg and discovers that Rachel has contacted Camp Half-Blood for help. The campers have infiltrated Nero’s tower via Nico’s underground route and are battling Nero’s forces. The trogs have eaten the Greek fire. Apollo finds Nero with Meg in his throne room. Nero reveals his Plan B: He aims to flood his tower with poisonous Sassanid gas, killing all the campers. Apollo signals to the trog-leader to disable the gas while he buys time with Nero. Nero tries to turn Meg against Apollo, but Meg announces that she is finally free from Nero’s control. Lu and Rachel arrive at the spot with Nero’s fasces. Apollo uses a surge of power to destroy the axe and kill Nero. However, before he dies, Nero announces that the power of the fasces will pass to Python, who has been controlling Nero all along.

Apollo must now head to the cavern under Delphi to fight the final battle with Python. He accesses Nero’s way to the lair and meets the great serpent in battle. As Rachel’s prophecy indicated, the only way to take down the powerful python is for Apollo himself to fall. Apollo blinds the serpent with an arrow and tackles him into the void leading to Hades. As they fall, Apollo begins to shed his mortal body. Python falls into Chaos, the primordial void, and disintegrates. Apollo faints and awakens in Olympus, restored to his godly form. Apollo’s father Zeus, the leader of the gods, congratulates him for completing his trials and saving the world from Python. Apollo realizes that his time as Lester has left him more human and empathetic and visits Meg and his other friends on earth. His trials concluded, Apollo promises to always watch over his friends and the reader.