The new case for Detective Agency No. 2 drops out of the clear blue sky – or at least from a third floor window. A thief has snuck in to an office building and has stolen a rare Japanese bookend from a room with an open window. No one knows who he is, where he has come from or where he’s gone. There is little doubt that this is a given mission for Detective Agency No. 2.

In Operation Ninja, Tiril, Oliver and Ocho are faced with sneaky dragons, phantom images, electrical voltage and – of course: ninjas.