Huddersfield, the 1990s. Deric Longden waits in the hospital. A nurse tells him that his mother has just died. In her house, she gathers her possessions, including two photos of her taken many decades apart. These can't help but trigger memories...
Deric helps his mother to negotiate a childproof pill container while she informs him that she's bought her late friend Kitty's house round the corner and needs to sell hers. After being told that she needs to arrange appointments for prospective house-buyers, she schedules them all for 5.30pm, laying on cakes and sherry. A middle-aged couple, Gloria and Fred Brooks, turn up early, and Mrs Longden makes a point of highlighting the house's various structural and electrical deficiencies, most resulting from her late husband's DIY attempts.
Deric arrives to find a party in full swing, with Gloria helping in the kitchen. She has been told every detail of Deric's life, including the death of his first wife. One prospective buyer was worried that it might have been in the house, and he reassures her. Driving home, Deric wonders whether his mother has a ley line running through her brain, bending logic at a tangent.
The next day, he hears that Gloria and Fred have bought the house. Deric and his wife Aileen help Mrs Longden move and unpack her 'treasures' - china figurines, most with bits missing. Deric worries about whether she can cope on her own.
Mrs Longden suffers a minor stroke, causing her speech to become slurred. Deric calls the doctor and insists on doing chores for her, despite her objections. When she wakes the next day, her speech is back to normal. She and Deric reminisce about their childhood and his father. She asks him to buy some Sellotape and a left-handed rubber glove. When he requests the latter at the chemist's, he immediately recognises him as Mrs Longden's son - five years ago, he had a damaged rubber glove, she bought the other at half price as a favour and has continued to buy odd gloves ever since.
Meanwhile, Mrs Longden is stuffing pieces of cotton wool into her taps and Sellotaping the stair carpet to the floor. Deric and Aileen return home to a telephone message urging them to ignore Mother's Day before complaining that "they're trying to get in the house again".
Concerned, Deric goes to see his mother, and discovers her modifications - and she's also removed her doorhandles and kitchen knives to stop the "little devils" getting in. Pressed further, she says that she once saw one in the bathroom, black and slimy like a slug.
Worried, Deric takes her to the hospital. She feigns ignorance in front of the doctor, and later chides Deric for telling him about the gremlins. She also says she's found the perfect residential home, but Deric says she'd be better off coming to live with him and Aileen.
Shortly afterwards, Mrs Longden has another major stroke - despite a speech therapist's best efforts, her speech is mostly incoherent. Deric tries to understand, but is baffled by one repeated word: "spongo". The doctor advises him to consider putting her in a home.
Deric tries to jog her memory by taking her to her favourite haunts. At a garden centre, she calls flowers "pretties" and fish "dogs". On the way home, she spots something that she insists is "Spongo" - the Spring Lea residential home.
Deric makes enquiries and discovers that while it seems excellent, it's far from cheap. He shops around, but is so put off by the dismissive attitude of another care home owner that he opts for Spring Lea. There, his mother is shown one of the present guests' rooms and then a forbiddingly bare one. Her distress turns to enthusiasm when one of the carers explains how her furniture will fit in.
Mrs Longden has another stroke, confining her to a hospital bed. The nurses initially chat amongst themselves, but Deric draws her into the conversation by showing them a picture of her as a young woman.
Back in the present, Deric decides to take the framed photographs of his mother home with them. He leaves her house for the last time.
