Shawn Mendes had only just turned 18 when he released his second full-length album, yet Illuminate sounds polished beyond his years—as if the teen heartthrob knew that he needed to fully break free of the social-media whirlwind that had brought him fame at the age of 14. His major-label debut, Handwritten, topped charts and bolstered a lively, young fanbase, but possibly due to his career’s rapid ascension, Mendes sang cautiously on it. Illuminate, by contrast, is confident, even brash at times, yet still in a mindfully caring way. Album standout “Treat You Better” presents him as a worried protector, the pitter-patter of acoustic guitar and drums propelling his voice to a breaking point, while on the deluxe version’s opener, “There’s Nothing Holdin’ Me Back,” he takes charge over a thrumming, jumpy guitar lick, bounding into pop conventions with a gentlemanly sensibility. It can seem like a bit of a shock when teen stars grow up, especially for young fans drawn to the purity of their idol’s image, but Mendes manages to toe the line well in Illuminate, singing about sex for the first time in songs that don’t actually sound too racy. “Lights On” and “Patience” have him worshipping his partners amid light, gentle acoustics. Mendes recorded the album in upstate New York, enlisting regular collaborators like songwriter and pop artist Teddy Geiger as well as new ones such as producer Jake Gosling, known at the time for his work on Ed Sheeran’s “Thinking Out Loud.” The atmosphere was relaxed and easygoing, allowing Mendes to write with ease and build off the styles of his modern troubadour icons, including not just Sheeran but also John Mayer, whose critically acclaimed album Continuum was a major influence. On the soulful “Ruin,” Mendes croons with the same swinging sincerity as his mentor with perhaps a bit more naïveté; “Don’t Be a Fool” and “Like This” similarly play into this bluesy softness. And then there’s “Mercy,” a rhythmically bursting track that most clearly identifies his new, realized balladeering persona: a man resigned to pine over his lovers with emotional acuity.