The path from earnest indie singer-songwriter to glossy, electronic mainstream pop star is rarely smooth. The artist who decides to take it usually finds it fraught with obstacles. There’s the risk of alienating your old audience in search of a new one that may ever materialise, the accusations of selling out or capitulation to record company pressure, and the snarky suggestions that something craven and desperate must be afoot, the latter fuelled by the longstanding belief that the world of the indie singer-songwriter is a righteous and noble one, packed with free-thinking integrity, and mainstream pop is living proof of Hunter S Thompson’s line about the music industry being “a cruel and shallow money trench … where thieves and pimps run free”.

All of which makes the recent history of Canadian duo Tegan and Sara fairly intriguing. “Make a change or this is going to stall,” runs one lyric on their latest album. It’s about a relationship, but it could easily be referring to their latterday career. Fourteen years on from their debut, with the release of 2013’s Heartthrob, they transitioned with apparent ease from the kind of artists who collaborated with the guy from Death Cab for Cutie and had their songs covered by Jack White to the kind of artists who collaborate with pop super-producer Greg Kurstin – co-author of Ellie Goulding’s Burn, Years and Years’ Shine and Adele’s Hello, among others – and appear on stage with Katy Perry: the album has been by some distance the biggest hit of their career. Moreover, they apparently found the pop world substantially less inclined to what a recent Buzzfeed feature called the “abject sexisim and homophobia” the twin sisters had faced in the arena of indie rock: it’s clearly more enjoyable to be feted by Taylor Swift than dismissed as “tampon rock” by Pitchfork, or, indeed, “quite lovely even if they do hate cock” by the NME.

Accordingly, Heartthrob’s follow-up crackles with an unmistakable confidence and poise. In an age when pop albums have a tendency to sprawl, the better to hedge their bets and offer up something for everybody, Love You to Death’s 10 songs clock in at a concise, focused 31 minutes. The choruses soar, the hooks reel you in, and it feels appealingly like the work of people who know exactly what they want to achieve and how to go about it. Kurstin is back on board, but the sound, while unmistakably radio-friendly and filled with neat touches – the woozy synth arpeggios that open Hang on to the Night; the stuttering drums that underpin That Girl’s lyrical uncertainty – feels pared down compared to its predecessor. If the album cover is suggestive of something that might have been released in 1982, then on Stop Desire or Boyfriend the music more or less matches, sounding like a 21st-century reboot of taut, spare new-wave pop.

While you could hardly accuse Tegan and Sara of coyly skirting around the issue of their sexuality in the past, it seems at least faintly telling that on Love You to Death, they’ve started augmenting their genderless love songs with lyrics that are explicitly about women. “All the girls I’ve loved before told me they signed up for more,” offers BWU, a song that ruminates on gay marriage: “Keep your name, keep your dates, keep your faith.” “You treat me like your boyfriend,” protests Boyfriend. “But I don’t want to be your secret anymore.” It’s tempting to say that neither lyric is quite as striking as the blunt examination of the sisters’ own tempestuous relationship on White Knuckles: Tegan and Sara might well be the first artists in history to offer up an epic EDM ballad about twin sisters beating the crap out of each other: “Excuses for the bruises we wear, black and blue now, breaking each other like knuckles in a fight”.

Indeed, for all Tegan and Sara’s adoption by the queens of teen pop, Love You to Death feels like a distinctly grownup album, unafraid to explore nuanced, mature themes. There’s something unflinching about 100x’s description of a failed relationship, and there’s a disturbing darkness lurking around Dying to Know: if you were the ex addressed in the lyrics, you’d strongly consider applying for a restraining order, or at the very least changing your mobile number.

That Buzzfeed profile also found the duo – who once doubted that gay women could ever make it into the US pop charts at all – wondering how far their newfound success might go, whether they might end up headlining Madison Square Gardens or the O2. Maybe, maybe not; the pop world is pretty fickle, after all. But listening to Love You to Death, it’s certainly not impossible to imagine.