Watch on Soap2day. Written by Terry Nation, Robert Hardy plays the eponymous hero of this 1972 one-off BBC drama; an occult detective who travels around in a lavish, bulletproof locomotive called 'The Tsar'. Along with his assistants Thomas and Caleb (Julian Holloway and John Rhys-Davies) Baldick is called in to investigate the latest in a series of brutal deaths at a desolate abbey.