In autumn, George goes underground, digging below an oak tree to see how its roots extract precious resources from the soil. And he sees why the oak's superstrong wood made it the perfect material for building some the most famous ships in naval history, including Nelson's flagship The Victory. In winter, George discovers the sophisticated strategies the tree uses to survive gales and bitter frosts. He finds out about the oak's vital role in architecture, showing how some very familiar sights, such as the tower of Salisbury Cathedral, are in fact giant oak structures.
In spring, George investigates how the oak procreates, spreading its pollen through the countryside. He discovers the incredibly sophisticated strategies it uses to withstand savage onslaughts from predators hellbent on eating it alive. In summer, George uses a high-powered microscope to see the hundreds of species that regard the oak as their home. Humans too rely on the oak for their own form of 'sustenance'. Whisky gets its unique flavours from the oak wood barrels in which it's matured.