The Ghosts is a novel written by Antonia Barber in 1969. It was shortlisted for the Carnegie Medal. It was filmed in 1972 as The Amazing Mr Blunden  with Laurence Naismith as Mr Blunden and Diana Dors as Mrs Wickens.
Mr Blunden, an elderly solicitor, visits Mrs Allen, a widow who lives with her three children Jamie, Lucy and the baby, in Camden Town, London, England. He tells her that his firm are looking for a suitable person to act as a caretaker to an old, abandoned house in the country until such time as the descendants of the original owners can be traced. When Mrs Allen leaves the room to tend to her baby, Mr Blunden mentions to Jamie and Lucy that there are rumours that the old house is haunted but that ghosts can often appear as ordinary people, perhaps children like themselves, and that ghosts are often people in need of help... Jamie and Lucy confirm that they wouldn't be scared of ghosts that appeared in that form and would help, if they could. Before Mrs Allen returns, Mr Blunden leaves, giving Jamie an old, faded card for the firm Blunden, Blunden and Claverton, where Mrs Allen should call the next day to inquire about the post.
The Allens visit the firm, which, surprisingly, is called Blunden, Claverton and Smith. The solicitors are puzzled at Mrs Allen's visit, since the job has not been advertised, but are nonetheless delighted to have found someone to take the job in spite of the rumours of ghosts, and soon the family find themselves living in the caretaker's cottage at Langley Park.
Lucy explores the house alone. In the attic she thinks she hears voices in the distance - but can't understand what they're saying. The woman who comes in from the village to clean confirms that they're the ghostly voices of children, just children, and nothing to worry about.
One morning soon after, Lucy is walking in the garden, gathering flowers. She suddenly becomes aware of a heavy, oppressive feeling and the warning song of a blackbird. Her eyes can't seem to focus, but she thinks she sees two transparent figures walking towards her through the mist that hovers over the lawn. She panics, screams and runs to Jamie who returns with her to investigate. Everything appears normal until, suddenly, they both become aware of the oppressive feeling and the repeating, hypnotic blackbird song again. And, again, the two figures are walking towards them through the mist. As they draw nearer the figures solidify into a young girl, about their age, and a younger boy.
Jamie and Lucy are relieved to meet what appear to be two ordinary children, albeit that their clothes seem a little old-fashioned. Only after talking for some minutes do they notice that the newcomers cast no shadows on the sunny path...
The new arrivals - Sara and Georgie Latimer - explain that they are not ghosts in the ordinary sense. They have come from a hundred years in the past when they lived at Langley Park. Their guardian, their uncle Bertie (a sensual, dissolute and penniless man), has fallen in love with a music-hall performer, Bella Wickens, and moved her mother and father in as housekeeper and caretaker to the house. However, the mother - Mrs Wickens - has determined to murder Sara and Georgie so that Bertie will inherit the family wealth - currently held in trust until Georgie comes of age. The children learn of Mrs Wickens' scheme and attempt to convince the family Solicitor - a certain Mr Blunden - of their danger. Blunden reacts violently and negatively to the news and the children are locked up, out of sight and out of mind.
One night, by the intervention of some supernatural agency that the children do not understand, they are led to the library of the house. There they find a book containing the recipe for a charm - 'A Charm To Move The Wheel Of Time'. By brewing the infusion and drinking it the children will be able to move through time to find the help they need. Sara and Georgie ask Jamie and Lucy to come back to their time and help them escape the fate that awaits them. Jamie and Lucy agree -although Lucy is less sure than Jamie. Sara gives them the recipe for the charm and arranges to meet them the next day. She and Georgie disappear back to the past...
The next day, in the local cemetery, Lucy and Jamie find the grave of Sara and Georgie and are disheartened. The sexton tells them that the children died in the fire that razed the house to the ground. However, they have brewed the potion and go to meet Sara and Georgie as arranged.
Only Sara is waiting for them. Georgie has upset Mrs Wickens and been locked in the cellar. Sara is keen to get back to him. At that moment, Mr Blunden arrives. This is the spirit of the Mr Blunden who ignored the pleas of Sara and Georgie and who is suffering, now, because of their deaths all those years ago. He has the opportunity to put things right and he promises Jamie and Lucy that he will keep them safe in the past; that any pain that must be suffered will be suffered by him. Sara confirms that she has forgiven Blunden. She is also aware of the grave in the churchyard. Jamie and Lucy drink the potion. The world around them swirls and goes black...
...and they find themselves back in Sara and Georgie's time - a hundred years before.
Mr Blunden tells them that, for a while, things must go on as they did before, but that when the time was right he would appear and help Jamie and Lucy save Sara and Georgie. Indeed, for a while, things do progress as they did, but eventually Mrs Wickens drugs the children and they sleep as Mr Wickens starts a fire in the library beneath the nursery. Tom, the gardener's boy, attempts to rescue them and manages to climb up the outside of the house to the nursery window. By now the fire has taken a firm hold and Jamie cannot get into the house to effect a rescue from below. Just as he's losing heart, Mr Blunden appears, takes him by the hand and leads him through the flames. Jamie feels nothing, while Blunden is clearly suffering both his pain and Jamie's and the guilt of a hundred years.
Tom, Sara and Georgie escape the house, but as Jamie attempts to leave he becomes trapped. As Lucy stands outside crying for Mr Blunden to help him the world around her swirls and blackens - and she finds herself back in her own time.
Searching the ruins of the house she finds Jamie, unconscious.
Some time later, with Jamie still ill, Lucy attends church and wanders through the cemetery afterwards. There, instead of the small stone marking Sara and Georgie's grave, she finds a tall granite memorial to Mr Frederick Percival Blunden who died to save the children in his care - a hundred years ago. They did it! They saved Sara and Georgie!
She returns home. Her mother tells her that Jamie is awake. She runs to his room and the two talk about their journey to the past.
When Jamie is well, the family receive a visit from one of the Solicitors at Blunden, Claverton and Smith. It seems they have traced the true owners of the house. Jamie and Lucy are sad, knowing this means they will have to leave, until the Solicitor explains that Sara Latimer married Tom the gardener's boy, emigrating to America, whilst Georgie inherited the house. It seems that Sara's daughter married a man named Allen and that - in fact - the true owner of the house is Jamie. Sara was their great-great grandmother.
Jamie runs off to explore the grounds anew, now as their owner. Lucy goes upstairs to the attic where she hopes, now she belongs to the house, that she will understand what the voices of the ghosts are saying...