Protomartyr have commandeered a boat. The Detroit Princess usually ferries boozy crowds up and down the Detroit river while hosting Motown revues and high-school proms, but tonight the city’s punks have taken over.

Instead of booking cover bands to play the Temptations and the Supremes, Protomartyr have convinced Canadian hardcore three-piece Metz to rip chunks out of the main ballroom, while electro-clash goths Adult belt out dancefloor broadsides below deck. It’s a sweaty, fun and incongruous mess, and Protomartyr’s lead singer, Joe Casey, is just happy no one has died. “I thought with that many drunk people onboard, something was bound to go horribly wrong,” he confesses the morning after.

Watch the video for Protomartyr’s single, A Private Understanding

It turns out the only casualties are someone who was hit by a wayward drone-cam, and drummer Alex Leonard, who only made it on stage thanks to an emergency IV drip that assuaged a badly timed bout of flu. The cruise was a celebration of the post-punk group’s fourth album, Relatives in Descent, which is an attempt – in the words of a press release – to dissect “the unknowable nature of truth, and the existential dread that often accompanies that unknowing”.

“I’m writing lyrics about how the world is kind of fucked right now, in terms of politics, but I don’t want to be so obvious,” says Casey, who acknowledges that it is a short leap from “nature of truth” to “fake news” and the unavoidable: Trump. “We wanted to make a point of not going out of our way to talk about it, because that’s what everyone is doing,” adds guitarist Greg Ahee.

“Obviously, we’re disgusted with what’s happening and Trump’s a dipshit,” he says. “But it feels so cheap to – and I’ve seen bands do this – write a song called Trump Sucks or Not My President. It’s like, we already know that, say something else. Most of us are on the same page about that. It just feels so easy to criticise this monster; maybe dig a little bit deeper.”

“That stuff ages badly,” Casey adds. “You just want to establish the mood.” That mood is, unsurprisingly, one of foreboding. Since their first releases in 2012, Protomartyr have attracted followers with the angular guitar of Ahee, the ballast of Leonard and bassist Scott Davidson, and Casey’s existential portraits, sketches of social mores and tales of urban decay.

Their last album, 2015’s The Agent Intellect, saw them installed in end-of-the-year charts, and contributed to them being declared rock’s “great white hope”. “Someone had a deadline,” deadpans Davidson. Over the course of four albums, Casey has created a psychogeography of Detroit, from tracks about corrupt local politicians (Bad Advice) and injury claims lawyers (I Forgive You), to others about local environmental pollution (Windsor Hum) and the tourists who flock to the city’s dilapidated buildings (Come and See). The band and the city are irrevocably linked, but it is a symbiosis they are not entirely comfortable with.

“I open ourselves to it by singing about Detroit,” explains Casey. “I’m not singing about Detroit because I think it’s the most interesting city in the world, I’m singing about Detroit because that’s where I’m from. I am just reporting on what’s going on around here. It’s not really Detroit. It’s my limited experience. I’m not a spokesman.” In a city that is more than 80% African American, Protomartyr know that a “literary punk” band isn’t exactly representative.

Ahee starts reciting Detroit musician Moodymann’s spoken-word intro to his 1997 track I Can’t Kick This Feeling When It Hits. It’s a barely audible two-minute homage to people from the city, who put up with its ups and downs, and Ahee believes the band are following a long tradition of Detroit techno acts that have had to wrestle with preformed ideas of the city and its inhabitants.

“There’s always been a lot of pride from people about Detroit, and now there’s a lot of defensiveness, because no one likes someone from the outside telling them who they are and what they’re like,” Ahee says. “I think those techno guys were the first people to deal with that and they’re still dealing with that. They show more pride than anyone.”

Protomartyr performing in 2014

We are talking at a Monocle-approved hip hotel near the city’s waterfront. It’s part of Detroit’s much-touted rebirth, which came after its much-publicised decline. Ahee recalls a conversation the band had with a music video director who visited Detroit for the first time after being told to expect a war zone. “He’d heard all the stories and he got here and the first thing he saw was a subway car turned over and everything looking post-apocalyptic,” explains Ahee. “Then he found out they were filming Transformers 4 and it was just all set design. The point is, somebody – based on what they’ve heard about Detroit – can see that and believe it. Like Joe says, we talk about what we know and what we’ve experienced and it’s certainly not representative.”

“It’s basically me trying to figure out what the last year meant to me,” adds Casey in reference to the album. “It seems like a weird time to be alive, but I suppose living through the hundred years war was a rough time to live in, too.”