It is just before World War 1. Dorothy and Walter Hollis are twins whose father is the butler at the Big House.
They strike up a forbidden friendship with lonely Master George, and are desperate to help him when his father goes missing.The sailing ship tree becomes their secret refuge.
Everything changes with the arrival of Tweenie, a young maid, as a friendship develops between her and Master George.
The two plan to stowaway to Australia to start a new life but Master George leaves the ship before it sails because his missing father reappears.
Years later, George does go to Australia, finds Tweenie and marries her.