David Zimmerman traces the origins of the Tizard Mission with Britain's initial attempts at technical co-operation in the First World War and unsuccessful efforts to restart it in the late 1930s. He highlights Winston Churchill's prominent, yet remarkably inconsistent, role in the story and the often tumultuous diplomatic relations with the Roosevelt administration, and shows how important British generosity was to the eventual success of the mission.

Among the secrets Britain revealed was the cavity magnetron, which made microwave radar possible.

Zimmerman reveals how the Tizard Mission established an effective system of teamwork for Allied technical and scientific co-operation, a teamwork that proved to be a crucial factor in Allied technical superiority. He demonstrates that the mission marked the beginning of the much longer story of Anglo-American scientific and technical co-operation, serving as a model for the international technical co-operation that continues today in organizations such as NATO.