Lisa and Nilly are fun characters who tried to find their friend Doctor Proctor.
So they travel by plane, and use the time travelling bath tub to try to locate him. Doctor did leave clues on where he had been and they did try to follow his trial.
But that's not it.
It is the way these children acting like children and find solutions only children could.
As a fan of Jo Nesbo, one would be curious on what kind of children books he would write.
He wrote like how he wrote his other books, with a lot of fun plot twists. And running around with clues.
The good thing is, there are a lot of surprises as well. Surprise on what the characters thought as solutions, or the next move.
First clue, A post card.
Not to spoil the plot. The post card is illustrated and anyone could try to get the clue.
Then there are big guys. The big guys are obvious big guys as this is a children book.
They chase the children. And the children run and escape.
Traveling in bathtub is fun.
Also, the use of fart powder. One of the invention of the Doctor who give a person ability to fart with power.
Like speeding up a bike ride up the hill. Yes, that's part of the running around bit in the book.
Highly recommended for kids.