Exclamation marks are generally avoided by novelists. The convention, famously set out by Elmore Leonard, is to use no more than two or three of them per 100,000 words, a convention Elizabeth Strout does not heed in Oh William! With a Pulitzer Prize in her back pocket for her novel, Olive Kitteridge, Strout can do whatever she wants, and does. The exclamation mark in the title of Oh William! is only the first of several dozen that appear in the body of the novel, and not necessarily where you might expect to find them.

Oh William! Is the story of the marriage, long ago ended in divorce, between William and Lucy. The novel is short and sparingly written, but the experiences of several lifetimes are revealed in a series of sometimes shocking revelations. Lucy has brought to the marriage the trauma of a dismal childhood, but it turns out that William’s apparently happy upbringing was not what it seemed. The juggling act Strout performs with grammar animates the narrative in surprising ways – the many instances of drama land with the quiet thud of the full stop, while the exclamation mark appears whenever Lucy experiences a pang of emotion or empathy, which she often does.

This is the third novel to feature the character of Lucy, and a sequel to the Booker-longlisted My Name is Lucy Barton. In this incarnation, Lucy has just been widowed by the death of her second husband and finds herself trying to solve the mystery of her continuing and now platonic relationship with her first. “What is it that William knew about me and that I knew about him that caused us to get married?” That question can only be answered by understanding his story as well as her own.

Oh William! is not a book that you read so much as you experience it. Lucy’s progress through her own life is so viscerally described that it feels like a physical journey. She might be walking through deep woods, light occasionally falling through the trees in the form of those exclamation marks of joy and love. The darkness lurking everywhere is the darkness of Lucy’s past, a legacy of emotional abuse and extreme poverty that has stalked her ever since. “I always thought that if there was a big corkboard and on that board was a pin for every person who ever lived, there would be no pin for me,” she tells us.

“Lucy comes from nothing,” her mother-in-law Catherine says, as if poverty were a place, which perhaps it is. Lucy’s childhood home in rural Illinois was a garage in a field of soybeans and before moving to a tiny house. “Very bad things happened in the garage and then later in that tiny house,” she says, but declines to say what. The trauma of Lucy’s childhood is ever present in her life, but it’s mitigated by instances of love. There’s a very moving episode from her past when the school guidance counsellor stops to buy her new clothes as she drives her to college. “I will always – oh always! I will always love that woman.”

The miracle here, as evidenced by all the exclamation marks, is the capacity of love to exist within damaged lives. Lucy is even prepared to allow for the fact that her appalling mother may have loved her, but it’s her love for her daughters, and theirs for her, that is most heartening, allowing them the luxury of an emotional freedom that amazes her. They have “the gift of tears”, she tells us, in one of the book’s many breathtakingly beautiful passages.

Lucy and William have been divorced for many years, and she tells us that “at times in our marriage I loathed him,” but her tenderness towards him persists. She’s touched by the sight of him in trousers that expose his ankles – “Oh William!” – and by his stooped walk. Lucy is a writer, and she’s been through therapy, so she’s good at observing things in herself and others, like the “ping” she registers when she sees William’s wife talking to another man at his birthday party. Often it’s in retrospect that Lucy understands the significance of something she’s observed, with the result that she only belatedly comes to see the forces that shaped her marriage to William. “This is the way of life: the many things we do not know until it is too late.”

Elizabeth Strout attributes the success of her work in part to a course she once took in stand-up comedy. It had occurred to her that what’s funny is true, so she set out to discover what was funny about herself in the hope of mining her own truth. The novels that followed are remarkable in the clarity of the insights they pull from the confusion of human existence. Strout has found a singular way of telling the truth about life as it is lived. To journey with her is a profoundly moving experience.