The world is growing ever smaller. There are less places to hide and less space to think. Nothing is private. It’s a notion that Belgian quintet Balthazar felt keenly as they traversed the world touring their 2012 album Rats. It was an intense period where they clocked up the sort of hard road mileage that can make or break a band but Balthazar’s two songwriters, Maarten Devoldere and Jinte Deprez, emerged emboldened. As Jinte explains, “we know each other’s darkest secrets now. We grew together. You live together as each other’s brother and sister. We actually discovered we really like each other.”

Lives lived in each other’s pockets has left its mark on Thin Walls, the stunning new album from the five-piece who are completed by Patricia Vanneste, Simon Casier and Michiel Balcaen. “Thin Walls is all about touring and never having any privacy,” says Jinte. The songs were written in a hazy hyperactive state between shows. Balthazar’s previous two albums, 2010’s Applause and the calculated, searing alt-rock of 2012’s Rats, were created in a slow, considered manner back home. This time round, the band had to fit in writing sessions whenever they had a spare day off. “When you’re on tour, the mood is very restless and chaotic,” says Maarten. “Life on tour is kind of weird, everything is prepared for you and you drink way too much. If you write with a hangover, then you write differently…”

The result is the band’s most instinctive and quietly feral record yet. It is, says Jinte, a product of the surroundings in which it was made, “less intimate” and all the better for it. If their first two albums came from the head, this one is straight from the gut. As well as the title being a nod to the prying eyes of the modern age, it’s also a literal description of how many of these songs were born: Jinte and Maarten had rented rooms in an old monastery next door to each other and the thin walls between the rooms meant they could hear every idea the other was working on. “If he had a new melody, I could hear it before he’d played it to me,” says Maarten, “so I had an idea for a song before I’d actually heard it properly.” The monastery would house the duo for a couple of days here and there before they would hit the road again, where hotels and their tourbus also became songwriting workshops. “We had to find a new way of writing on this record,” says Maarten. This constant state of flux, says Jinte, has given these songs a “lust for life”.

The dynamic between the two frontmen is key to Balthazar’s magnetic pull. The pair met busking in the town square as teens but over the course of two albums they have honed an intricate songwriting partnership that hits paydirt on the new album. “We’re really complimentary,” says Jinte. “We’re totally different songwriters but then not cos we like the same kind of stuff. For example, if I try to write a Kanye West song, he’ll say “let’s do this Leonard Cohen thing over the top!” It works like that a lot. We’re each other’s best critics.” Over the years, they have inherited each other’s songwriting personalities: when they began, Jinte was the rock guitar player who wrote riffs and Maarten the lyrically dexterous singer-songwriter. “We’ve been working together for so long that we’ve influenced each other,” says Maarten. “Now, he works hard on the lyrics and I write rock songs…”

After self-producing Applause and Rats, this time the band travelled to the UK to work with Blur, Depeche Mode and Elbow producer Ben Hillier and Jason Cox (Gorillaz, Massive Attack) at Yellow Fish Studios in Lewes. Over the course of their three-week stay, they got to bear witness to the psychedelic freakiness of Bonfire Night in Lewes. “It was loud and there was lots of booze – everything you need to get a record going,” says Jinte. Putting an album into the hands of someone else was a welcome relief: “it gave us peace of mind not being responsible for the production,” says Maarten, “working with Ben gave us way more space to focus on the music.”

The resultant record is a career-best: a grizzly indie-rock album full of nocturnal grooves and mesmeric melodies. Jinte and Maarten’s lyrical themes always seem to land on the same page and these are songs of anxiety and hope and love and fear. Usually it’s a girl causing any or all of those emotions. “I’ll always write about girls,” says Maarten. “That’s the thing that gets me writing.” “I like getting older cos it’s getting a bit clearer that nobody knows anything,” says Jinte. The devil is in the detail: it is an album of simple things. “Nobody’s lives are a Greek drama,” says Jinte. “It’s never about the big stuff, it’s always the small stuff.”

The album opens with the filmic glide of Decency, a track about “being in a band” and one that sets the eerie, captivating tone of the whole record. These are songs that dare you to scratch beneath the surface: Then What is a joyously ragged rocker about being so desperately in love that you realize your happiness depends on someone else (“which isn’t a nice feeling,” says Maarten), the fuzzy glam stomp of Nightclub explores the poetic, bohemian beauty of being drunk and trying to impress girls and the melancholic croon of Dirty Love is about the inevitable doom of falling in love on tour. Themes interlock and weave in and out of each other: the soulful, solemn Bunker is about a girl who’s moved away, the woozy Wait Any Longer is about moving town yourself. The subjects of doubt and love are returned to in Last Call, I Looked For You and So Easy, whilst the orchestral blast of final song True Love is a suitably bittersweet sign-off. “It’s about lust, and how it can screw everything up,” says Maarten. “I guess that’s a running theme.”

Thin Walls is a beguiling snapshot of life in your mid-twenties, an album that puts Balthazar on the cusp of a big breakthrough. There is a slow burning beauty to their songs. These stirring vignettes will take the five-piece to bold new places.

Later this year the band will be playing at Pinkpop.