An amazing and inspiring story of a small, driven R&D engineering company that struggles to convert theory into working hardware, make the bridge from doing "research" to "building products", that eventually pulls itself out of operating on the brink of bankruptcy, while offering the world a clean, renewable source of energy, the Solar Heated Free Piston Stirling Engine. Shelton does a great job in conveying the personalities, the financial and technical challenges overcome, and the dramatic events that allowed Sunpower to survive through some very trying times.