Based on an animation film, the book explores the possible origin of ‘zero' as used in mathematical calculations. The story is a fictional take on actual research done on the subject. A merchant living in Takshashila (north-western India) finds he has to do calculations all the time. But without ‘zero', it is a complicated process indeed. One night, he falls asleep on his papers. When he wakes up, sunlight is streaming in through the latticed window, throwing circular beams of light on his calculations. An idea is sparked off. Eureka! The people of the time – trade, trade routes, architecture, dress styles, dyes used, and so on – were also researched for authenticity in the film, which carries into the illustrations. The earthy colours and textures provide a vivid complement to the text. Bhojpatra (birchbark), used for manuscripts those days, has been used as a backdrop for an old-world feel.