The prolific Scottish novelist Alison Kennedy once observed that while children’s authors can say they “just make things up” because “it’s great fun”, other novelists have to dress up writing as something much more serious. In this, Kennedy’s first book for children, the sense is of an author gleefully letting herself off the leash. From the opening scene in which Bill – a shy, fastidious badger – finds himself trapped inside a bag which smells “as if someone had been crying inside it … and then maybe after that had been sick” and is being carried by someone with “a heart full of nails and sand and nastiness”, we are in a surreal, funny and vividly imagined world.

What follows is a bonkers plot involving Bill, a daffy, sandy-haired man called Uncle Shawn, and a group of extravagantly named llamas (Guinevere, Ginalolabrigida) lured to Scotland on a false promise of sunshine and lemonade. Shawn is the animals’ only hope of rescue from the hideous McGloone family, who plan to let Bill perish in a caged dog fight and bake him and the llamas into pies.

Kennedy relishes her technicolour villains (Maude and Ethel McGloone could out-nasty Dahl’s Aunt Sponge and Aunt Spiker) and shares David Walliams’s knack for psychological observation (the sisters live in “a cottage full of failed knitting”). But the big delight here is the prose. Chapter books for younger readers (this is recommended for 7+) often come couched in bland language, but this brims with exhilarating imagery. Ethel’s eyes are “like old, bad eggs”. Uncle Shawn’s are “as blue as two pieces of sky on a good Bank Holiday by the sea with extra crisps and ice-cream”. Highly recommended.

• Uncle Shawn and Bill and the Almost Entirely Unplanned Adventure by AL Kennedy is published by Walker (£8.99). To order a copy for £7.64 go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99