Visionary aircraft designer R.J. Mitchell (Leslie Howard) struggles against opposition to develop his revolutionary fighter design and eventually his own failing health. Together with test pilot Geoffrey Crisp (David Niven) Mitchell succeeds in getting his inspirational design into production. The Spitfire was the most successful warplane of its generation; the very symbol and image of British pride and power, as the killer fighter of the decisive air battle of World War 2, the Battle of Britain.