The story revolves around a 10-year-old girl named Tamsyn, who has been orphaned and is being raised by her uncle, a shipowner in Bideford.

She is brought to live in London by another uncle, who works as a swordsmith, or armourer, being the owner of the house after which the novel is titled.

The mother of the house tells them the tale of Tam Lin on Halloween, which parallels the theme of a girl who struggles to pursue her dreams.

She watches tall ships at the docks, consistently showing a strong interest in sailing, which she shares with one of the Armourer's sons, Piers.

"[2] Kirkus Reviews saw The Armourer's House as "A gay portrait of London in the days of Henry VII... " and "one exuberant adventure after another" with "The pictures by C. Walter Hodges ... endowed with a warmth that complements the stories.