The story is about a twelve-year-old, Tom, who, while staying with his aunt and uncle, slips out at midnight and discovers a magical, mysterious Victorian garden where he befriends a young girl named Hatty.

Pearce won the annual Carnegie Medal from the Library Association, recognising the year's outstanding children's book by a British author.

[2] In 2007, for a celebration of the Carnegie Medal's 70th anniversary, a panel named Tom's Midnight Garden one of the top ten Medal-winning works[3] and the British public elected it the nation's second-favourite.

[4] Tom is a modern boy living under quarantine with his aunt and uncle in a city flat, part of a converted building that was a country house during the 1880s–1890s.

He shouts Hatty's name in desperation, before his Uncle Alan finds him and puts the events down to Tom sleepwalking.

The following morning, Mrs Bartholomew summons Tom to apologise, only to reveal herself as Hatty, having made the link when she heard him call her name.

The final reunion between Tom, still a child, and the elderly Hatty is, many have argued, one of the most moving moments in children's fiction.

[8] Researcher Ward Bradley, in his review of various modern stories and books depicting Victorian British society, criticized Midnight Garden for "romanticizing the world of the 19th-century aristocratic mansions, making it a glittering 'lost paradise' contrasted with the drab reality of contemporary lower middle class Britain.(...)

[9] Time slip would be a popular device in British children's novels in this period, although this device arguably started with Mark Twain's adult satirical comedy A Connecticut Yankee in King Arthur's Court (1889), followed by Rudyard Kipling's children's book Puck of Pook's Hill (1906, with a succession of slips back into Britain's past), and Margaret Irwin's Still She Wished for Company (1924, combining ghosts and time slip), and Elizabeth Goudge's The Middle Window (1935, with a time-slip back to the era of Bonnie Prince Charlie).

This was an event that occurred on 10 August 1901 in the gardens of the Petit Trianon, involving two female academics, Charlotte Anne Moberly (1846–1937) and Eleanor Jourdain (1863–1924).

Moberly and Jourdain claimed to have slipped back to the last days of pre-Revolutionary France, reported in their later book An Adventure (1911).

[2] For the 70th anniversary celebration in 2007, a panel of experts appointed by the children's librarians named Tom's Midnight Garden one of the top ten Medal-winning works, which composed the ballot for a public election of the nation's favourite.