Within the walls and under the floorboards of Orchard Farmhouse live three mischievous mouse brothers (a.k.a. the trins) who create constant commotion.
When Mr Gray is caught by a cat, Mrs Gray is left alone with her three babies. She remembered her old granny's words, 'The gravest of all mousely sins – is to produce a set of trins!' Trins is another name for triplets, and this is the story of Mrs Gray's boys, Tom, Dick and Harry.