At some point during the inhumanly cold Himalayan winter straddling 1965 and 1966, a peculiar collection of box-shaped objects — one sprouting a six-foot, insect-like antenna — plummets nine thousand feet down the sheer flanks of a remote peak. Ripped from its moorings by an avalanche, the jumbled apparatus slides down a funnel-shaped hourglass of hard snow and shoots over a black cliff band, careening a vertical distance six times the height of the Empire State building.

The boxes come to rest on the glacier at the mountain's base. One, an olive-drab casing the size of a personal computer, begins to sink. Then, trailing a robotic dogtail of torn wires, it slowly burns through the snow, melting into solid blue glacial ice, eventually disappearing beneath the surface, and never seen again.

No one actually witnessed this event. But as you read these words, nearly four pounds of plutonium — locked in the glacier's dark unknowable heart — are almost certainly moving ever closer to the source of the Ganges River. Eye at the Top of the World, provides a harrowing present-day account of Takeda's expedition to solve the mystery of Nanda Devi.