In the film -- directed by music video director Grant Singer and released ahead of Mendes' upcoming fourth studio album, Wonder -- the 22-year-old singer takes fans behind the scenes of his rigorous, 105-show 2019 tour, Shawn Mendes: The Tour, as well as back to his hometown and inside his relationship with Camila Cabello.
The pair met when Mendes and Fifth Harmony both served as opening acts on Austin Mahone's 2014 Live on Tour, but didn't become close until another tour found them making music together. As Cabello explains in the doc, she was backstage at Taylor Swift's 1989Tour when she saw Mendes again, and the two instantly sat down in his dressing room and started writing "I Know What You Did Last Summer" -- a track that, upon its release in November 2015, would become Mendes' second major hit and Cabello's solo debut single as she broke away from her girl group.
The pair stayed friends for years before taking the next steps in their relationship, but Mendes sweetly reflects on their bond in a candid moment in the doc, admitting that "every song I've ever wrote" has been about Cabello.
Years later, they would collaborate again, dropping their steamy duet, "Señorita," in June 2019 -- the middle of Mendes' worldwide tour and the filming of In Wonder -- as they went public with their relationship and navigated life and love in the spotlight, sharing some of the journey on camera.
Here are a few more of the sweetest "Shawmila" revelations from In Wonder:
How starting as friends has been a benefit to their relationship.
Mendes opens up in the doc about how, despite any rumors, he and Cabello were just friends for many years before making things official -- allowing them to build a solid foundation of support.
"For the past four years, just being friends and not being able to see each other very often, to finally being able to be together, she was always there to look out for me, as a human being," he explains. "She's got my back, and I think that's what your partner's for."
How they understand each other on an important level.
Mendes returns to his Ontario hometown before playing the biggest show of his career so far at Toronto's Rogers Centre, a venue he's been idolizing for many years. While sitting in his childhood bedroom, where he filmed the Vines that started his ascent to musical stardom, he reflects on how he and Cabello have a shared understanding about fame.
"We were watching videos of us when we were like, 16," he recalls of a recent moment with his lady love. "We both got so caught up in it, and we looked at each other and were like, 'I don't feel good.' Because we were taken right back to that insecure, unsure 15-year-old."
"We just looked at each other and were like, 'We feel weird right now, don't we?' And she's like, 'Yeah, we do.' And I'm like, 'I'm so happy you know why. 'Cause I don't know if I could explain this very well to other people.'"
How they're finding their own version of domestic bliss.
After meeting as teenagers rising towards pop stardom, Mendes marvels at the fact that he and Cabello are now sharing their success, and living together in her New York City apartment "for the very first time alone."
"It's pretty cool, she's renting an apartment in the West Village, so we're staying there," he notes. "Making eggs and trying to figure out how to use a Keurig. Normal things, you know? This is really cool, to just be like, a 21-year-old guy."
"We wake up in the morning, and [then] we have to get in separate SUVs to head to the same place," he adds with a laugh. "It's like almost living a taste of a normal life in the least normal-life way."
How every song Shawn has ever written has been about Camila.
The heartwarming moment comes as Shawn is reflecting on his relationship with Cabello -- ahead of their first performance of "Señorita" at the 2019 VMAs -- and marveling at her reaction to his admission that he's been writing songs about her for years.
"My song comes on the radio or something and the fact comes up that it's about her. I'm like, ‘Yeah, it's about you. Everything's about you. They've always been about you,'" Mendes recalls. "She goes, ‘What do you mean?' I'm like, 'They're all about you. Like every song I've ever wrote.' And I'm rhyming off the songs, like, 'Treat You Better,' all these songs. She's like, 'Oh my god.' This whole time, I thought she knew."
However, as their relationship evolves, Mendes reveals he's not sure he'll be able to fully capture it in song.
"I don't think I'm going to be able to write songs that really do it justice, that can really capture the things and the feelings with her," he admits. "I think it's like when you see the moon, or stars, and you try to take a photo of it with your iPhone, and then you just can't. It just doesn't look good. And you're like, ah, it's not supposed to be captured. It's just supposed to be for us."
Shawn Mendes: In Wonder is streaming now on Netflix.