Mummy faces the daunting prospect of the school holidays and a chaotic social calendar with her usual blend of exasperation and dark humor. The protagonist, a mother of two, finds her attempts at a peaceful summer vacation derailed by the demands of her children and the unexpected complexities of her family life. She must navigate the challenges of organizing a school Christmas fair while dealing with her father's much younger wife and her own narcissistic mother, all while attempting to maintain her sanity.

The novel is positioned as a humorous take on the challenges of modern motherhood, building on the success of the author's previous works. The premise suggests a narrative filled with relatable domestic chaos and witty observations about parenting and social obligations. Readers can expect a lighthearted exploration of the pressures faced by mothers, likely delivered with a sharp, comedic voice. The story appears to focus on the protagonist's attempts to manage her family and social life with a blend of exasperation and resilience.