Twins Tulip and Ali have noticed that their mother seems to have become particularly sleepy and distracted ever since her boyfriend Sturgeon moved in. They decide to run away to the hospital where their mother works as a doctor but are rumbled on the way there by their grandmother Nan-Nan while they are assisting a lady who has collapsed. Having acquired basic medical know-how from their mother the twins know exactly what to do but are surprised to find their grandmother Nan-Nan has discovered their whereabouts so quickly. She returns the girls to school much to their disgust. She often looks after the twins while their Mum is working but she has a mysterious past and the twins are eager to find out more even though Nan-Nan is evasive.
Back at school several of the teachers begin to fall asleep too and the twins become suspicious that this seems to happen when Sturgeon has been at the school, supposedly conducting a research experiment. Convinced he must have something to do with the mystery malaise, the twins together with sidekicks Zac and Jay, and Nan-Nan who turns out not to be quite as she seems, set out to solve the mystery.
The witty repartee between the twins is particularly well-done and Nan-Nan is comic genius. The plot zips along, perhaps a little too mad-cap in places but it all makes for an accessible and enjoyable read. And the story is just as much about intergenerational and family relationships as it is a mystery to solve. A feel-good and lively mystery which offers a slightly different take on the usual detective genre. There are plenty of medical facts sprinkled throughout the story too and a helpful glossary at the back of medical tips.