1956, the Scottish Highlands: Aaron and Robbie, a schoolmaster's son and a farmer's boy, are fast friends with a shared passion for diving, but very divergent ideas of what they will do with their lives.

Meanwhile, Mark and Ally, bright pupils at Edinburgh's grandest private school, are aspiring to make change in the world - one through high finance, the other on the political stage.

And Joseph, heir to an Aberdeen trawler-fishing dynasty, is brooding over whether his true ambitions are set higher than his father's succession plan.

For each of them, the discovery of oil under the North Sea will make their dreams achievable. But behind the promise and temptation of 'black gold,' there is a price to be paid; and they will discover that oil can overthrow relationships, turn friends into foes, and even put lives in peril.