With the collapse of the Soviet Union, Buran, the Soviet response to the NASA space shuttle programme, during the Cold War, was discontinued. Twenty-five years on, a photographer found one prototype of the five that were built, in an abandoned hangar of the Russian launch site in Kazakhstan. The Buran that made the programme's only orbital flight is no more, but nine-year-old Leo is convinced that someone hid it, somewhere in Siberia, and that he will find it. With Elizabeth, he rummages through satellite images, travelling the world in search of traces of the vessel, all without leaving the French seaside, where he spends his holidays. What they need is someone who helps find lost objects. A Siberian tiger will steer them in the right direction. This is a treasure hunt that blurs the limits between imagination and reality and whose sense of urgency contrasts with the long indolent Summer days.