They were out of their depth, out of breath, and out of time. It was 1973. Two men were trapped in a crippled submarine 1,700 feet below sea. They only had enough air to survive for two days. On the ocean's surface there was a hastily assembled flotilla of rescue ships from both sides of the Atlantic. The world held its breath to await word of a rescue. In a routine dive to fix the telecommunication cable that snakes along the Atlantic sea bed, their mission had gone badly wrong. There was a catastrophic fault on board the Pisces III, and Roger Chapman and Roger Mallinson's mini-submarine went tumbling to the ocean bed almost half a mile below. The crippled sub and its crew were trapped far beyond the depth of any previous sub-sea rescue. They had just two days' worth of oxygen. However, on the surface the best estimates for a rescue of these men was a minimum of three days' time.