A young woman, who desperately wants to raise a child, seeks out the help of a local witch, who gives her the grain from a barley. From this seed, a tulip grows up in a night, and when the mother kisses the petals, they open to reveal a tiny girlchild sitting inside, no bigger than her thumb. This small humanoid is called "Thumbelina" (Tomme-Lise in the original language), and is sufficiently cared for. She sleeps in the shell of a walnut, and it is arranged for her to row in a small boat in a saucepan set on a table. For a while. During the summer, she sleeps at an open window, and a toad jumps in, deeming this delicate girl fit to be wife for her son, and carries her off.
Thumbelina finds herself awake on the leaf of a water lily, and is promptly presented to this male toad, whom she finds ugly. But wedding is set, and the toad mother carries off her bed, leaving Thumbelina alone and upset. The fish notice her plight, and feel sorry for her. They gnaw off the stem of the leaf, and the leaf drives off down river — "thus, Thumbelina travelled out into the world". She makes friends with a butterfly, and uses her apron string to tie the butterfly to the leaf, using it to steer the leaf. Then, a scarabee spots her, finds her pretty and carries her off, to present her to the other insects, who dismisses her as ugly. She is promptly dumped, and left to live alone in the forest all summer — actually having a useful life, until autumn sets in. Food gets scarce, and a field mouse finds her huddled and freezing in a corn field, and takes her in. She is allowed to live there, but has to work for her lodgings. The field mouse has a neighbour, it turns out: a mole. This mole is reckoned to be a fine gentleman, but he hates sunlight and lives far underground. The field mouse agrees with the mole that Thumbelina is to marry him. She does not like him, but seems to be stuck with him.
In the tunnels between the caves of the Mole and the mouse lodgings, Thumbelina finds a swallow nearly frozen to death. She tends to it, and it survives, to come out in the spring, while Thumbelina is to prepare for her wedding. At the end of summer, this is meant to happen, but Thumbelina walks out one last time to greet the departing birds. The swallow shows up, and Thumbelina begs to be carried away — which the swallow does, leaving the Mole behind. The swallow carries Thumbelina to a southern land, where she is dropped off in a meadow full of flowers, and in each of the flowers resides a small fairy, being of her own size. The fairy prince woos her, and this time Thumbelina gives in, to be his princess. She is granted a pair of fairy wings (actually from a fly), to spin around with the others. The fairy prince also gives her a new name: Maya, which sounds a lot better than "thumbelina". The swallow grieves because he also has grown to love her, but is also content that she finally is happy. At last, the Swallow returns to Denmark, where he has a nest close to the window of an author, and from this swallow, states the author, "we have the entire story"...
Thumbelina provides examples of:
- Abhorrent Admirer: The toad, the Scarabee and the Mole. The first one is rude and stupid (as well as abhorrent), the last one is lofty, arrogant and boring. The Scarabee is actually quite nice to her, but dumps her because his fellow scarabees think she is the abhorrent one.
- All of the Other Reindeer: The scarabees, who actually taunts Thumbelina for not looking like them. She is left alone, actually crying because she believes like them that she is not pretty. Fair enough, she has no idea what she looks like, and noone to compare herself to.
- All Work vs. All Play: The Field Mouse vs the Swallow. At least she sees it that way. See also Boring, but Practical. It is, as ever in a story by Andersen, a question of values.
- Author Avatar: The Swallow. Andersen often associated himself with this bird.
- The Beautiful Elite: The Mole, seen from a rodent perspective. He is rich, and he has (omigosh) a velvet coat!
- Be Careful What You Wish For: The mother specified that she wanted a "teeny weeny child". The witch delivered on her Exact Words.
- Big Damn Heroes: The Swallow, coming in for the rescue in the nick of time — carrying Thumbelina away to a better fate.
- Boring, but Practical: The attitude of the Field Mouse. She is pragmatic, and is on the side of the mole when it comes to the "impractical" Swallow, which both ground dwellers think deserves no better, for just singing his life away without hoarding food for winter. She scoffs of the fact that Thumbelina has little interest in marrying for money. But Thumbelina states quite bluntly that the Mole is "boring".
- Born from Plants: Thumbelina is essentially a wingless fairy born from a flower, and she gets wings part way through her story.
- Break the Cutie: Thumbelina is close to breakdown a number of times — but when she eventually finds her own kind, she seems to have shaved it off. Other Andersen Heroines fare worse than her, though.
- The Cameo: Andersen, of course. He is the author at the end of the story.
- Cosmic Plaything: Thumbelina. She is more or less dragged from place to place, and only interferes a few times, which benefits her: She takes action to make sure the butterfly can steer the leaf she is on, and later, she tends to the Swallow, and eventually decides to leave with him.
- Exact Words: As stated in the opening lines: "once there was a woman who wished for a small, small child..." She states the same to the local witch, who gives the woman exactly what she wished for: a humanoid no bigger than a thumb.
- Fairy Sexy: Thumbelina invokes this trope again and again, although she does not understand it herself. It is implied she is a fairy, sans the wings, of course, but sadly misplaced in Denmark.
- Fish out of Water: Thumbelina for most of the story. Only at the end, she finds her own species.
- Harmony Versus Discipline: Thumbelina versus the Field Mouse. The Field Mouse "disciplines" Thumbelina to some extent, but she bails out as soon as the Swallow gives her an opportunity. As it were, Thumbelina has lived in harmony with nature all summer, until all was barren and there was nothing left to eat.
- Incorruptible Pure Pureness: Thumbelina is so kind and pretty, everybody takes a shine to her. She has the potential to be abused, though. Luckily, the "abuse" is cut off by a number of circumstances.
- Inter Species Romance: One-sided, and therefore also defied. It seems every male animal involved wants Thumbelina, but the arrangement is always made over her head or behind her back.
- I Want My Beloved to Be Happy: The Swallow leaves Thumbelina with this thought in mind.
- Kidnapped While Sleeping: The mother toad kidnaps Thumbelina while she was sleeping on the windowsill.
- Lilliputians: Thumbelina is described as being no bigger than her mother's thumb, not to mention the fairy prince.
- Meaningful Rename: Thumbelina finds a new identity (and a people), and is renamed Maya.
- Mole Miner: The Mole, of course, having a lot of space, caves and tunnels.
- Narrator: The Swallow narrates the Thumbelina's story to the (unnamed) author who lives in the attic close to his nest in Copenhagen. The author is obviously Andersen himself, and thus, by default, the Swallow also is an Author Avatar.
- No Celebrities Were Harmed: Reckoning that Andersen cast himself in the role of the Swallow, the fact that Thumbelina is said to have a beautiful voice, leads us to think of his unrequited love for Jenny Lind, the Swedish singer.
- No Name Given: Apart from Thumbelina, all characters are unnamed.
- Plot-Relevant Age-Up: Thumbelina is described as a child when she is revealed inside the tulip. When the female toad arrives and carries her away, she does it because she deems her fit to marry her son. How much time did really go by? Presumably enough to age her at least to adolescence, but the reader might be excused for thinking that mere days have passed. Andersen didn't elaborate this point much and makes no mention of a years-long time skip.
- She's a Man in Japan: The Swallow is female in many translations (such as Russian, German, French, Italian). Its all the question of its grammatical gender.
- Sliding Scale of Idealism vs. Cynicism: Strongly on the Romantic/Idealistic side. The "romantic" attributes, like beauty, sunlight, high flights (the Swallow embodies romanticism), overcomes the more "realistic" ground dwelling animals and their practical, almost cynical attitudes.
- So Beautiful, It's a Curse: Thumbelina. Much of the problems she has to face, comes from the fact that somebody wants her company because of her beauty. This dumps her with one Abhorrent Admirer after another.
- Take That!: Danish bourgeois customs of marriage, and the fact that girls had little to say in the matter.
- What Happened to the Mouse?: Several times, because we follow the route of the heroine, and the people she escapes from, or is robbed from, is left behind. Thumbelina at least feels sorry for the Butterfly who is still tied to the leaf, and for the kind Field Mouse. Her initial human "mother" is never mentioned again, however.