Sara Pascoe’s debut novel draws you in slowly and then all at once. The first line is fairly standard. The second, a little less so. Still, if you skimmed the first chapter, it would be easy to think you knew what you were getting: your basic, by-the-numbers quirky-girl-meets-boy romcom. This is because that is exactly what our narrator wants us to think. She’s trying very hard to be basic! And she would love this to be a romcom. “I hope since our chat he thinks I’m normal,” she confides cheerily. “I told him I was several times.” She is Sophie; he is Chris. They met working “on the buses” taking tourists round London; now Sophie works in a pub and Chris is buying a drink, and he doesn’t remember her at all. Or does he? Part of the joy of Weirdo is not knowing what to expect, or rather in having your expectations subverted by Sophie’s smoothie-maker of a mind. You put your preconceived ideas in, and Sophie – or rather Pascoe – shakes them all about. “It occurred to me that Australia might be a trick,” Sophie thinks, stepping off the plane there. “The people could be actors. But that was the jet lag. I accepted that Australia was real, because the trick would cost many millions and why would anyone invest all that money just to humiliate me?” Sophie accepts it, but she’s not completely convinced. Sophie takes nothing for granted. The world is all askew, and Sophie steps through it tentatively, as braced as someone walking on a waltzer. This off-kilter perceptiveness manifests as the kind of precise observations you might expect from standup Sara Pascoe: the crowdfunding hell of modern weddings, the bitter rivalry of unlikely sisters, the kinds of shit jobs people have when they move to London without a plan. Sophie has worked on the buses, as a “scarer” at the London Dungeon and now in a horrible unnamed pub chain. All of these are very funny. Pascoe is equally good, though, on the unfunny bits. The viciousness of schoolgirl bullying resonates throughout, and the depth of family trauma – even when played ostensibly for laughs – sticks with you long after the riff’s got old and everyone’s gone home. “I was staying very still,” Sophie says while her alcoholic mother rages and hurls the washing-up liquid at her. “The peanut inside the M&M, coated and separate, away from the action.” There’s a touch of Mark Haddon’s The Curious Incident of the Dog in the Night-Time here; plus, perhaps, a very funny, candid smattering of Louise Rennison’s beloved teen diarist Georgia Nicolson. Pascoe has written about her adolescent love of Jostein Gaarder’s Sophie’s World, and it’s not hard to draw the line between his naive, careful philosopher Sophie and hers. If you combined those three teenagers, and aged them up 15 years, you might find something of her narrator’s pure, strange tone. “If I was in a film I’d be better looking,” she muses. “And that’s why men in films like women in films even when they’re terrible people.” Sophie thinks a lot about being in a film. Like her Gaarder namesake, she thinks a lot about being observed generally. “I used to think my mum could see me through the cat,” she says. What she doesn’t say, not then anyway, is that she still sort of thinks that might be true. “That’s why I keep so many supporting documents,” Sophie says. “For my future biographer.” The funny thing is, of course, that Sophie is sort of right. We readers are watching her every move; and the author, eavesdropping on her character’s most perverse and private thoughts, is watching her too; and the author herself has made a living out of being watched and listened to and observed. It’s a philosophical loop-the-loop that comes straight from Gaarder, only older, and darker, and with considerably more booze. “You can’t experience being alive without realising that you have to die,” young Sophie says in the opening pages of Gaarder’s book. “But it’s just as impossible to realise you have to die without thinking how incredibly amazing it is to be alive.” Sophie Amundsen gets letters from a mysterious philosopher, while Sophie Collins’s are from debt collectors, but they are both looking through a glass, darkly, at the universe and themselves. “I am alive and I exist and one day I will die,” Pascoe’s heroine tells herself near the end of the novel. “But at the moment, this is happening.” Does Weirdo wobble a little towards the end? Is there too much plot? Could you lift out, fully, one or two entire storylines? Sure. It’s a debut novel. Like all debut novels, there is a lot going on. Unlike many debut novels, though – and certainly unlike most debut novels by the already famous – this one will stick with you for a long time. Weirdo by Sara Pascoe is published by Faber (£14.99). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.