When plastic toys are locked in the cupboard, they become real, living beings, resulting in Omri befriending an 18th-century Iroquois (Haudenosaunee) chief named Little Bear (Little Bull in some editions).

As the series progresses, Omri and his friend Patrick learn more about the cupboard's powers, including its ability to transport people to and fro through history.

[5][6] At one time, classrooms and libraries widely accepted the book,[7] to the point that it was part of the teaching curricula for children at the novel's recommend reading level.

Omri is particularly affected when a plastic figure of an elderly Native American chief dies of shock upon being brought to life.

Nevertheless, Patrick uses the cupboard without Omri's knowledge, bringing to life the plastic cowboy, who turns out to be a man named Boone from an entirely different place and time as Little Bear.

The antagonism comes to a head when Omri and Patrick introduce the duo to television; when Boone cheers the slaughter of Native Americans in an old Western, Little Bear shoots him in the chest with an arrow.

Omri brings to life the figure of a World War I medic, who turns out to be a man named Tommy Atkins from the trenches of France.

[5][6] Kirkus Reviews observed, "The first book had a fine balance between childish desire to play with the tiny figures and awareness that, though small, they were real people who ought not to be so manipulated.

[12] According to Freedom to Read, the book was challenged by a school board in Kamloops, British Columbia, and was temporarily removed from public libraries on the basis of the "potentially offensive treatment of native peoples.

[16] In 1992, Doris Seale, a Santee Dakota, Abenaki and Cree librarian, wrote, "My heart aches for the Native child unfortunate enough to stumble across, and read, these books.

[19] Omri and Patrick intervene aggressively in Little Bear's home world, Kirkus observed in contrast to the first book, noting "Feisty, likable characters and the precise logic by which Banks evolves events from her premises make this one of the better recent fantasies.

At first Patrick seems to have banished the memory of the tiny people from his mind, but then reluctantly shows Omri that he still carries the plastic figure of Boone in his pocket.

The boys buy several more plastic Iroquois figures from the local shops and bring them all to life with the cupboard to serve as Little Bear's army.

After Little Bear and his troops are sent back, a casual comment by Boone prompts Omri and Patrick to wonder if it is the key which is magical, rather than the cupboard.

The tipi is set on fire, but Patrick brings him back in the nick of time, only to find half Omri's hair singed off and his face blistered.

Patrick and Omri bring back their Marine friend Fickits, along with a complement of troops, and set them loose on the skinheads, who are peppered by tiny machine-gun fire, causing them to flee.

Omri has grown ever more reluctant about using the key's magic powers to meddle with history, but he finally agrees to "hide" Patrick's true whereabouts in the large chest he has in his room.

Emma agrees to borrow the medical set for him and to keep silent about the magic, on the condition that she be allowed to bring to life a plastic person of her own.

Boone and Ruby Lou realize they are stranded as tiny people in the far future, unable to return home without the key.

He uses the magic to summon all of the group's tiny friends for Boone and Ruby Lou's wedding before sending everyone home for what he promises will be the final time.

Afterwards Omri asks his parents for a safe-deposit box, into which he puts the key, the cupboard, the figurines of Little Bear and his family, and a copy of his story, leaving them for his children to find.

"There's not much chance to stereotype Native Americans here, as Banks was charged with earlier, but Jessica Charlotte is certainly a caricature of a music-hall singer; one wonders whether it's reasonable, or merely foolish, to deplore such shorthand in popular fiction.

Jessica possesses a power called the Gift, which she uses to read the future by pouring lead into water and interpreting the shapes it makes.

She also gave him a little person to care for, a servant girl named Jenny from the 1800s who sought to escape her home life after she lost her position.

Bert had no idea that he was robbing a woman of her only valuables and promises Omri that he will return the jewellery box in the past in hopes of changing the future for the better.

Tom has fallen from the roof and is on the verge of death, but asked for Omri to tell him the final secret: before she died, Jessica had him search for a plastic figure of herself.

After reading that, Omri's dad figures out that Jessica Charlotte could possibly create them a magical copy of the car key so they can travel back in time.

Old Clan Woman, the oldest and wisest member of the tribe manages to scare them off with Omri and his father's help, but she is killed by the two retreating men.

She reveals that she, like Omri, has inherited some of Jessica Charlotte's psychic powers and, seeming to read his mind, explains that she's known the truth since the beginning but has kept it to herself.

He first sends the wampum belt back and senses through his psychic powers that Little Bear and his tribe have successfully and safely reached Canada and reveals this to his father along with the fact that his mother knows the truth.