Sydney, 1942. The war is coming to Australia - not only with the threat of bombardment, but also the arrival of refugees from Europe. Dreamy Columba's world is growing larger. She is drawn to Ellery, the little boy from far away, and, together with her highly practical best friend Hilda, the three children embark on an adventure through the harbour-side streets - a journey of discovery and terror, in pursuit of the mysterious blue cat.