Rejected by his doctrinaire socialist mother and father while still a baby, John Denby is sent down south to live with his wealthy grandfather and grandmother. Educated at a private school and cosseted at home, all he knows is the leafy London suburb where he lives and his self-created world of steam train models and the Scripture Union. Then a sudden tragedy strikes and he must return to the 'desolate', 'proletarian' North to live with his deeply unsympathetic parents and to attend an 'experimental' state school that his father has helped set up.