The story is set on Emblem Island, where every person is born with a lifeline on their palms revealing the course of their life. Most people also bear an emblem, a skin marking that dictates a specific talent or gift. Those born without any emblem are called the Markless. The narrative alternates between the main story and folktale interludes from the island's mythology that foreshadow encounters and explain traditions.
Twelve-year-old Tor Luna lives in the village of Estrelle. His mother, Chieftess Luna, leads the village, and Tor shares her leadership emblem: two purple rings around his left wrist. He resents the marking; his true passion is swimming. Each morning he sneaks to the Sapphire Sea, where salt water strangely never bothers his eyes or throat. Only his best friend Engle, whose sightseeing emblem lets him see great distances and in the dark, knows this.
On New Year's Eve, the island's most important holiday, inhabitants write wishes on leaves and throw them into a bonfire, hoping the wish-gods will grant them. Tor has carried his wish in secret for months: he wants to exchange his leadership emblem for a water-breathing one.
The next morning, his leadership emblem is gone, replaced by a dark, blinking eye on his wrist. He recognizes the marking from
The Book of Cuentos, a collection of the island's myths, as a curse. Melda Alexander, the only other student in Tor's leadership class, catches a glimpse and offers to help if she can come along. She has rare sapphire-blue eyes and wears a blue pendant necklace.
Melda leads them to Mrs. Libra, a hermit whose rare know-all emblem means she knows everything within her geographical range. Mrs. Libra identifies the marking as a curse cast by the Night Witch, a figure Tor believed existed only in fairy tales, and reveals his lifeline has been shortened to roughly one week. Both Melda and Engle have touched the marking, and the curse has latched onto them: Melda now bears an eye on her wrist, Engle a pair of lips on his. Their lifelines are shortened as well. Mrs. Libra directs them to another know-all in the city of Zeal.
In the tunnels beneath the mountains, trolls attack until Engle discovers a glowing fairy whose light turns them to stone. In Zeal, they are brought before Queen Aurelia, whose puppeteer emblem lets her force others to obey. Aurelia will help them find the Night Witch if they kill her. Threatened with violence, Tor agrees. Aurelia's adviser Jeremiah gives them a map of the Shadows, a vast area drained of color where the witch resides, and a silver dagger for slaying her. When Jeremiah demands Melda's pendant, which contains a rare drop of color, the lips on Engle's wrist speak, commanding them to jump. They leap from the balcony and escape on a passing balloon.
The trio theorizes that the voice belongs to a wish-god and that Tor has been sent on a Grail, a legendary quest giving markless children a chance to earn a unique emblem. Tor devises a plan:
The Book of Cuentos was written by a storyteller who traveled the island and ended at the Night Witch's location, so they can match the book's stories to real places on the map and trace the storyteller's path. Melda trades for a compass and an enchanted light bulb storing sunlight.
Their journey takes them through dangerous locations corresponding to stories from
The Book of Cuentos. In Zura, a bioluminescent rain forest, they encounter a massive two-headed serpent and are led to safety by a local boy. A healer saves Tor from a poisonous frog and gives them a sack of crystals, warning never to let them touch the ground. In the desert, they nearly die before a silver falcon guides them to an oasis that proves to be a captivate, a magical trap set by enchanting aquatic creatures. Tor falls under the spell until Engle breaks through by invoking Tor's sister Rosa. At the Scalawag Range, Tor hurls the crystals to the ground, unleashing elemental chaos that sweeps them to safety on an ice slide. In Frostflake, Melda saves a snow village by smashing the enchanted light bulb to release stored sunlight. They are then hosted by giantesses, where Tor resolves to find an alternative to killing the witch.
They cross into the Shadows, where oppressive darkness erodes their morale. Tor breaks down and turns back, giving the dagger to Melda, who refuses to quit. When Tor and Engle hear her scream through the curse linking them, they track her to a tower of emblem-thieves, markless people who kill to steal others' powers. They rescue Melda and dozens of prisoners. A freed telecorp, a person with a teleportation emblem, enchants a coin to take them home when the journey ends.
At an abandoned mill, they rest while Engle's curse spreads alarmingly, dark veins crawling across his body. Tor discovers a key symbol on the spine of
The Book of Cuentos matching a mark on the map, leading them to Etler Key, the storyteller's great-great-nephew. Etler explains that his ancestor Vero Key found the Night Witch and was cursed to forget nearly everything. Etler suspects Vero loved the witch and provides directions deeper into the Shadows.
The Shadows tests them with rules carved painfully into their skin: "Don't stop" (287), "Don't Look Back" (291), and "Don't die" (299). Hallucinations tempt them to pause. A seductive voice offers Tor the emblem he always wanted in exchange for betraying Melda; he refuses without hesitation.
At the Lake of the Lost, a goblin demands the color of Melda's eyes for passage. She agrees, her irises turning gray. On the lake, skeletal bonesulkers attack and drag Engle underwater. Melda shatters her pendant against the boat, releasing its drop of color. The lake flashes sapphire blue, stunning the creatures long enough to rescue Engle. Melda stays with the wounded Engle on shore while Tor heads alone toward the cliff.
Tor dives into a dark pool and encounters three pearls: Power, Riches, and Sacrifice. The Sacrifice pearl shows him dying but his friends freed. He chooses it and begins to drown, but the water propels him into a cave where a woman reveals herself as the Night Witch. She confirms Tor is not on a Grail. Drawing on Etler's suspicion, Tor deduces she is the moon from the tale "The Sun and the Moon" and that she loved the storyteller.
The Night Witch confirms this. She was born with two emblems: one that kills and one that restores life. After emblem-thieves murdered her father, she hunted them for years, accumulating markings. She loved Vero but erased his memories to protect them both, making herself a monster in his stories. She is the island's true wish-god and the source of the Shadows. She cursed Tor deliberately, needing someone who did not want power. His choice of Sacrifice proved his worthiness. She declares him her heir: he will become a Wicked, a person who bears multiple emblems, and inherit all her powers to protect the island from a coming evil.
Tor refuses and draws the dagger, which transforms into a crystal sword. They fight briefly, but when he has a chance to strike, he chooses not to. She shatters his sword, confirming he never could have killed her. She removes the curse from all three of them and names him the Wicked of Emblem Island. She warns that darkness targets his village, then leaps from the cliff, her body splitting into birds that fly in every direction.
Tor descends to find Engle healed. Their mothers arrive, having tracked them across the island. They agree to keep Tor's status secret and teleport home using the telecorp's coin. A month later, the three friends meet on the beach each morning. Chieftess Luna has enacted policies to help struggling families. Tor has sprouted his first new emblem, the fish marking for water-breathing, hidden beneath long sleeves. Their lifelines have grown since the curse's removal, and all three lifelines now look almost identical. As they sit together, a girl with a water-breathing emblem washes ashore. Her green eyes fly open long enough to speak two words before she loses consciousness: "They're coming" (328).