Director Lionel Jeffries adapted this follow-up to The Railway Children (1970) from an Antonia Barber novel entitled The Ghosts.
A near-destitute widowed mother, Mrs Allen (Dorothy Alison), and her two young children Jamie and Lucy, take up the mysterious offer from genial lawyer Mr Blunden (Laurence Naismith) to become housekeepers at a crumbling, partly fire-damaged country mansion called Langley Park, that is rumoured to be haunted.
Young Jamie and Lucy meet the mansion’s resident ghosts one afternoon in the gardens; the spiritual orphans Sara and Georgie were once the mansion’s heirs.
They recount the tale of tyrannical Mrs Wickens (Diana Dors), the mother-in-law of Bertie (James Villiers) and his wife Bella (Madeleine Smith), who plotted the children’s death in order to claim their inheritance. They were killed in the fire at the mansion one hundred years ago.
Jamie and Lucy are given instructions on how to concoct a magic potion made from woodland herbs that will transport them back to 1818 so that they may help right a 100-year-old wrong.
When researching into the death of Sara and Georgie in the local churchyard they once again meet Mr Blunden who explains how he was the guardian of Sara and Georgie but failed to act on their pleas of impending danger, and it is his ghost that instigated the Allen family taking up residence at the mansion.
Jamie and Lucy consume the magic potion and are sent back in time to the night of the children’s death so they might assist Mr Blunden in rewriting history. Veering between suspense and pantomime, the movie ends with a satisfying twist and the half-promise of a sequel (which never materialised).