The proximity of the publication of David Nicholls’s sixth novel, You Are Here, to the screening of the superb Netflix remake of One Day gives the new book an added sense of poignancy. If One Day (2009) saw Nicholls as a writer in his mid-40s looking back nostalgically on the loves and losses of twentysomethings, here we find him approaching 60 and turning his attention to a couple either side of 40. If One Day was angst and high drama, the setup here is softer and, initially at least, more obviously comic. But the shadow of the earlier novel, of Dexter and Emma’s will-they-won’t-they romance, hangs over this book. Michael Bradshaw, a geography teacher reeling from a series of personal setbacks, most painfully his separation from soon-to-be ex-wife Natasha, decides to walk Alfred Wainwright’s famous coast to coast path through the Lakes and the Pennines. His happily married colleague Cleo, despairing at his inability to move on, turns what was going to be a solitary excursion into a party. She invites a motley gang along for the first leg of the walk: Conrad, an “absurdly attractive” pharmacist; Cleo’s taciturn teenage son, Anthony; and Marnie Walsh, a copy editor, “aged 38, of Herne Hill, London”. There was supposed to be another friend, Tessa, whom Cleo had invited as a potential match for Michael, but she drops out at the last minute. You Are Here is a great comic novel that also asks the reader to think about the place of humour in fiction: there’s a dangerous proximity throughout the novel between laughter and tears. The narrative moves from Marnie to Michael, short chapters with the close third-person perspective passing like a baton from one to the other (until, at the end, a lovely formal flourish, and a move to Victorian omniscience). Marnie’s chapters show how humour is implicated in the fact that she is lonely: “If she blinked off the face of the Earth no one in London would notice for several weeks.” She deflates moments of intimacy with laughter, showing both the carapace that a sense of humour can provide, but also how it can ossify, becoming a barrier between Marnie and those who might love her. Michael is more serious, more wounded, aware that his “sincerity invites ridicule”. Like Michael, Marnie has been through a failed marriage, although Neil, her ex, is a cartoonish figure, vain and proprietorial. At first, as they set out from the Irish Sea, Marnie is drawn to Conrad, who has come to the mountains in jeans and trainers. He and Marnie are both definitely urban, although she, at least, has come with a good supply of Gore-Tex and an over-large rucksack. Despite the fact that Marnie finds something “powerfully anti-aphrodisiac about the English countryside” and that Conrad seems like a drip, sparks develop. Michael is always there, though, in the background, looking noble. Partly, it’s that Marnie returns to Michael again and again, her warmly funny descriptions of him drawing us to him and to her in equal measure: “His face… had something old-fashioned about it, a kind of crumpled nobility, like someone leading a doomed expedition… ”; later, she says he is “handsome in an old-fashioned way, someone from a sepia photograph whose only mistress is the sea”; he “looked like someone who’d spent a year filming puffins in the Hebrides”. Marnie is only planning to walk the first three days of the trip, but then Conrad drops out, and Cleo departs with Anthony, and Marnie and Michael, both experts at solitude, are alone together. Nicholls is superb on the landscape of this beautiful part of the world. The novel describes two seductions: the first is the mutual, if awkward and bumbling, romance between Michael and Marnie; the second traces Marnie’s reluctant acknowledgment of the sublimity of the countryside. As the pair make their way through the hills and valleys, and Marnie’s self-imposed deadline passes, we find ourselves inhabiting first one, then the other’s perspective, our sympathies tugged in alternate directions. We see how each stands in the way of a shared happy ending and how infuriating this is, how senseless. The reader becomes so invested in the outcome of this unspectacular, everyday, cagoule-clad romance that it makes the whole world shimmer with a kind of secret possibility, as if such narratives are everywhere, just out of sight. You Are Here by David Nicholls is published by Sceptre (£20). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply