In the summer of 2016, Architects were on a winning streak. The Brighton band, founded by twin brothers Tom and Dan Searle in the early 00s, had spent years slogging away on the metal circuit: now, they had two Top 20 albums under their belt, as well as the respect of their peers. Life inside the band, however, was less rosy – in fact, it was nightmarish. Unbeknown to fans, the group’s guitarist and main songwriter, Tom, had spent the past three years suffering from cancer. In August 2016, he died, aged 28.

For Dan, devastation came with a sense of duty. He needed to inform the band’s devoted fanbase – none of whom had the faintest idea Tom had been ill. So, against all his instincts, he broke the news in a long and heartrending Facebook update the next day. Posting something so intimate online felt “totally gross”, he remembers, sitting beside Architects frontman Sam Carter in a stifling east London office. “But what do you do? You have to address it, you have to say something”.

Over the past two years, Dan and his bandmates have experienced the disturbing and singularly bizarre process of grieving under the watchful gaze of their fans. “We’re not A-list celebrities, but people know about us everywhere we go in the world, and people want to talk about it everywhere we go,” explains Dan, Architects’ drummer. “And they might be crying, and they might want us to be really upset. I’m like, I’m sorry to seem like an arsehole but I can’t have this conversation, because this is my fucking brother.” In Sam’s case, such a public loss has been accompanied by a strange self-consciousness. “It’s weird because I could be with Dan walking through town and we could be pissing ourselves about something funny, but for that one second someone sees you and they’re like, ‘Oh they’re fine’. That’s not the way grief works and that’s not the way life works.”

Part of the reason behind this insidious air of surveillance is that Architects didn’t wind down in the wake of Tom’s death – instead, their slow-burn success ballooned into something much bigger. In February, they brought their dense and nuanced strain of metal, a grinding storm of apoplectic riffs and sandpaper howls, to the 10,000-capacity Alexandra Palace, north London; in January they will headline Wembley Arena. The latter is a landmark achievement that the band are struggling to process, but the numbers stack up: their comeback single Doomsday has racked up 19m YouTube hits since its release last year.

Now, Architects are gearing up to release Holy Hell, their eighth album and the first since Tom’s death. Sam and Dan discuss the record with eloquence and excitement – the pair are quintessential examples of the modern rockstar archetype: intelligent, self-deprecating and generally lovely – but they are also palpably nervous about its reception. Holy Hell acts as a both a meditation on grief and a tribute to Tom: his fingerprints are all over it.

“He might have written a song, or a song might just have a little bit of background ambience that is from him,” explains Dan, who says that drawing on his brother’s work prompted another dimension of angst, with the musician fearing he’d look like “this vulture feeding off the scraps of Tom’s demos”. The band also felt the pressure to make something impressive enough to ward off any patronising well-wishers. “We didn’t want the sympathy likes – we didn’t want people to be like, ‘You’ve been through so much, good work for trying,’” says Sam. Dan breaks into a mischievous smirk. “Because if we write a great record and get the sympathy likes, people won’t just think it’s a great record, they’ll think it’s world-class!”

Holy Hell isn’t simply a chance for Dan and his bandmates to prove their mettle – it’s also an opportunity for catharsis. Yet they are mindful that the album’s brutal, purgative honesty doesn’t impact negatively on the band’s more impressionable fans, particularly in the case of the album opener, Death Is Not Defeat, a song about the irrationality of the survival instinct. In the wake of Tom’s death, Dan says he began to wonder: “Why do we need to live? Who for, what for? And that was one where I felt really nervous, like I was green-lighting people to kill themselves or validate their suicidal thoughts, which was really not what I wanted to do.” Instead, the message is intended for Tom. “I just wanted to say to my brother, it’s OK that you died,” he says. “You haven’t let anyone down by dying – that’s just the way it is and I hope when I die I’ll see you.”

Amid the turmoil, there has recently been some joy in the Architects universe: in August, Dan and his wife had their first child. He sees a link between the trials of caring for a new baby – the sleep deprivation, the responsibility, the worry – and the anxiety that went into making Holy Hell. “I’ve just had to think: this is hard, but it will be worth it – I know it will be worth it because this is hard,” he says, landing satisfyingly on a sentiment that sums up both his new fatherhood and his painful, bittersweet quest to guide Architects into the future.