We meet the main characters of The Brink while they are driving together to Leavers. The dynamic in the LandCruiser is a microcosm of the week as it plays out: Nerdy Leonardo is panicking but trying to hide it. Footy jock Mason is goofballing, drinking, and secretly lusting after his best mate. High-achiever Kaiya is too practical for her own good, too practical to be the type of friend Valentina needs her to be. And Val is taking selfies and clinging to Jared: her boyfriend, their driver, the volatile sun at the centre of everyone's orbit.

As the story takes place during Leavers - the week-long party at the end of high school - the five protagonists aren't the only ones looking for a good time. But they manage to find a secluded, isolated island (no mobile reception!) to spend the week, with only a handful of other teenagers from their extended friendship group, and some shady adult locals.

Within this extended cast, the focus remains on the five, who all have something they want out of the week. I won't tell you whether any of them get it - but it's safe to say no one wants a dead body. Leonardo warns you on the first page: "It didn't start with the dead body."

So when the body appeared, halfway through the book, I was initially underwhelmed. I thought the novel had been entertaining and thought-provoking enough while focusing on the more normal dramas of teenage life: alcohol, angst, freedom, lust, betrayal.

I didn't think it needed Lord of the Flies-style antics thrown in - but then, wow. Little did I know. It didn't start with the dead body, and it didn't end there either.

When the stakes are raised, it's the (slightly exaggerated) locals who present the greatest physical threat to the teens. It's a credit to Sheppard's ability to get you thoroughly inside the heads of the protagonists that the impact of the physical danger pales in comparison to the psychological turmoil within and between the teens - especially Leonardo, Mason and Kaiya, whose vivid and distinct perspectives we hear in alternating chapters.

Toward the end the three become somewhat harder to tell apart - but that might mostly be a realistic illustration of the unifying power of catastrophe.

Sheppard doesn't shy away from the uglier bits of beings a teenager, and doesn't provide a pat, didactic solution, either. Instead - and this feels like a weird thing to say about a story driven by the raging hormones of teenage boys, replete with graphic scenes of "huge brown tits" and inconvenient stiffies - the exploration of masculinity and sexuality in The Brink is nuanced and subtle.

I'd recommend it to anyone who has ever been, loved, or raised a teenage boy.