In 1760, Guillaume le Gentil, astronomer to King Louis XV, sets sail for India. He hopes to record the transit of Venus, but rough seas - and war with the British - make his quest more complicated than he could have imagined.

Two hundred and fifty years later, anxious, lonely Xavier Lemercier chances upon Guillaume's telescope. As he looks out across the rooftops of Paris, he glimpses an intriguing woman with a zebra in her apartment. Then she walks into his office, and his life changes forever...