Mr and Mrs Twitcherly are sparrows: common everyday sparrows who live in an excavated nest hole in an ancient but statuesque oak tree in the garden of 18 Mulberry Road. Their twin sons, Furtive and Fearless, were named by David, the five year old who lived at number 18, according to their observed characteristics. Their neighbour in the oak is an absent-minded but kindly spotted woodpecker called Lemuel.
Their Great Uncle Ebeneezer invites them to stay with him for a holiday in his great elm, which is several miles from their home. Furtive and Fearless have many adventures whilst there, including an encounter with a Shrinker. He takes large swathes of the countryside, along with its wildlife, shrinks them, and puts them into his collection in a hidden and long-forgotten mansion deep in the forest.
Out on a jaunt one day, Furtive saves the life of and rescues a young female sparrow called Patience, who has been caught by a cat. She is the daughter of Old Benjamin, who is very similar to magical Great Uncle Ebeneezer (or are they one and the same?). During one of his visits to see Patience, Furtive is "drawn" into an exploration of the Shrinker's mansion. He becomes ensnared by the Shrinker's magic, and finds himself in one of his collection pieces. There, he meets an iridescent parrot called Archie, with whom he has a scary adventure or two.
David and his family move away from number 18 eventually, and the house is bought by the Carfax family, who, having no affinity at all with wildlife, cut down the oak to create more garden space. They have twin sons called Ballantyne and Barrington: naughty boys who enjoy tormenting the local wildlife. Eventually, they get their comeuppance, but not without upset for the Twitcherlies, who have to find a new home.
I feel sure that you will be able to guess from whom they receive help, after which they all ...