The Luck of Troy transforms the Trojan War saga into an original story focalised through the character of the twelve year old boy Nicostratus, the son of Menelaus and Helen. Having been brought to Troy by his mother when he was a baby, Nico grows up in the besieged city, with only hazy memories of Greece and his father, and a deeply conflicted sense of identity and loyalty. As the war’s impact intensifies, most of the Trojans reject and persecute him as a traitor, but he finds some comfort in the house of Antenor and his wife Theano, Priestess of Athena, and in a friendship with Priam’s youngest daughter Polyxena, who lives with the older couple much of the time. 

Green’s more traditional version, The Tale of Troy, published three years earlier in 1958, provides the framework for this more subjective retelling, which illuminates the personalities and relationships of the main characters of the myth. The book begins with a Prologue at Mycenae, featuring Hermione staying with her older cousins Electra and Iphigeneia during the funeral for their grandfather, King Atreus. Helen has recently eloped with Paris and Menelaus and Odysseus have gone to Troy to demand her return. Arriving back to Agamemnon’s Palace at Mycenae, the men discuss the impending conflict, making it clear that Helen’s abduction is merely a pretext for an inevitable political conflict between the Barbarians and the Greeks, East and West. 

The narrative then shifts to Troy in the tenth year of the war. Nico and Polyxena watch from the city walls as Hector kills Patroclus and is in turn slaughtered by Achilles. After Priam bargains with Achilles for his son’s body in return for its weight in gold, the children look on as the crafty inventor Palamedes constructs a huge set of scales below the walls of Troy. When the treasury is empty and Hector’s body still not balanced, Polyxena tosses down her golden jewelry, capturing Achilles’ attention. Nico discovers that his childhood friend has fallen for the Greek hero, and uncovers a secret arrangement, engineered by Antenor and the crafty Palamedes, to end the war by marrying Polyxena off to Achilles. But Paris double-crosses Achilles and shoots him with a poisoned arrow, and the Greeks stone Palamedes to death for his treachery. 

Nico is a witness to other intrigues. He observes Helen bathing the feet of a mysterious beggar whom she identifies as Odysseus, best friend of her first husband. As their resistance to Troy grows, Paris becomes increasingly hostile to both his stepson and his wife, but it is only after his death that they are in real danger. Helen is passed over to another brother, Deiphobus, who is abusive, cruel and violent. Nico realises that he "had hated Paris, but he hated Deiphobus a hundred times more, and with a new, fierce hatred that sometimes rather frightened him" (p. 131). Despite the risk, Nico and Helen assist Odysseus in stealing the Palladium, the special statue of the goddess Athena, known as the Luck of Troy for its reputed powers to protect the city in which it resides. But while Odysseus makes off with the statue through a secret passage out of the city, it remains uncertain whether he has taken the real artefact, or a convincing copy created by Theano. They know that Odysseus has a plan to bring down the city, but he has refused to share the details, asking only that Helen leaves a lamp burning in her window on the next moonless night. 

Nico and Helen are confined to her tower for the final weeks of the war, with vile Deiphobus counting down to his wedding day when he will hang Nicostratus the "treacherous Greek cub" (p. 148) from Troy’s walls to be picked apart by birds and dogs. Fortunately the wedding never takes place, as the Trojans awaken one morning to find that the Greeks have abandoned their camp. While Cassandra rants prophesies of doom, the massive wooden horse that they have left behind is dragged within the city walls. The Trojans feast and celebrate, and that night Helen is once again overcome with madness and persuades Deiphobus to take her to see the horse. There, she uses her unique powers for mimicry to call out to those hidden within using the voices of their wives. As the couple moves away, Nico watches as the hidden Greeks descend from the belly of the horse and move out to take the city. Drunk and dangerous, Deiphobus is about to murder Nico when Menelaus appears and slaughters his enemy. The family is reunited and Helen’s crimes are forgiven. Nico eagerly awaits his departure from Troy and the journey to his Greek homeland, which he imagines to be "the loveliest land on earth" (p. 171).

In spite of his more creative approach in this book, Green makes sure to highlight that "no character in the story is invented" (p. 10). However, in his final Author’s Note, he admits that the "actual part played in the story by Nicostratus is without direct authority from the ancient authors" (p. 173). A son of Helen and Menelaus is referred to in Apollodorus (Library 3.11.1), and Green explains that his intention was to "present the last year of the Siege of Troy as it would have appeared to this Greek boy of twelve or thirteen who had such exceptional opportunities of observing all that happened" (p. 174). The Luck of Troy establishes a literary tradition in which young characters witness the events of myth, and at times play an active part in the action. In doing so, child readers are given the opportunity to experience the same vicarious pleasure of watching and playing with myth. 

Nico’s character enables Green to explore different themes to those addressed in the more traditional Tale of Troy. As he comes of age, Nico struggles with his identity as a Greek within Troy, and feels conflicted in his loyalties to the few Trojans whom he knows and respects, and the unknown Greek warriors, including his father, who parade on the plain below the city. In this story there are good Trojans and bad Greeks. 

Caroline Cooney, author of the young adult novel On the Seas to Troy (2004), also has Helen bring her baby boy, this time called Pleisthenes, with her when she comes to Troy. But where Cooney’s Helen is a fearsome figure who treats her enemies with shocking cruelty and exalts in the fact that men are willing to die for her, Green’s Helen is a gentle, often despondent woman who grieves the burden of her beauty. Gill’s illustrations depict her modestly swathed in robes, with her face frequently turned away from the viewer. Helen says to her son:

"Oh, Nico, what is going to become of us when Troy falls? Will Menelaus forgive me – can the Greeks allow him to forgive me? Think how many have died in this war – all because of me. Whether it was my fault or not, it was all because of me! Oh, it would have been better, far better, if I had never been born!" (p. 53) 

Green’s Helen is victim both of the lusts of men and of the gods’ manipulations. Hermione blames the magic of Aphrodite for her mother’s madness: "She was drugged; she was walking in a dream; that evil Trojan pipe had taken away her wits" (p. 31). But though the narrative regularly references the powers of the gods, they do not appear as characters within the story. Instead, the story highlights links with the archaeological record, describing funeral rituals held within the beehive tombs at Mycenae, and including Palamedes’ message written in Linear B. 

Along with cowardly, indolent Paris and cruel, abusive Deiphobus, Palamedes emerges as the villain of the story. Odysseus finds it hard to forgive him for exposing his feigned madness on the beach at Ithaca, and Menelaus finds him "rather tiresome and effeminate" (p. 30). Green draws on a range of ancient sources including references in Plato, Virgil, and Ovid to flesh out his character, who speaks with an unattractive lisp. Palamedes is credited with clever inventions (including dice games to amuse the soldiers, and the scale upon which Hector’s body is weighed), but in his treachery and double-dealing he is unfavourably contrasted with Odysseus, who is both ingenious and heroic.