In the 16 years that elapsed since the Pastels' last full album, 1997's Illumination, they stayed busy with collaborative projects (2009's Two Sunsets made with Tenniscoats), soundtracks (2003's The Last Great Wilderness), and real life (Stephen Pastel established a record shop, Monorail, in Glasgow). During that time, the group's two core members (Stephen and Katrina) gathered many similarly minded musicians (including Gerald Love and multi-instrumentalist Tom Crossley) and slowly changed the way they approached their music. While still extremely melodic and based in pop structures, the (sporadic) work they did over those years grew warmer and more peaceful, the arrangements blossoming into tapestries with each inch filled with voices and instruments. Instead of sounding overstuffed, the songs felt like warm blankets of sound that instantly transported you to somewhere still and magical. Slow Summits is the beautiful culmination of this years-long expansion process, as the Pastels bring a full complement of collaborators (members of To Rococo Rot and Tenniscoats, Katrina's sister Alison, and Norman Blake, to name a few), a producer who knows how to wrangle the sound into something perfectly ordered yet still organic (John McEntire), new guitarist John Hogarty, and original member Annabel Wright to help make this the best-sounding album of their long career. Though some date back to the period just after Illumination, the nine songs here fit together like stones on the bottom of a stream, with gently meandering instrumentals ("After Image," the title track) balancing slowly unspooling, heartbreakingly sincere ballads (the Craig Armstrong-arranged "Kicking Leaves" and "Secret Music," which features a lovely cameo from Wright) and bobbing uptempo songs ("Check My Heart") swaying hand in hand with soulful midtempo groovers ("Come to the Dance"). The arrangements, too, interlock perfectly, with flutes peeping around the edges, Alison Mitchell's trumpet ringing out, the guitars playing off each other like old friends, and the extra bits, like handclaps, bells, and the occasional keys, adding just the right amount of autumnal color. Stephen and Katrina's vocals sound just right in this context: his understated croon hints at depths of passion without being obvious about it; her fantastically sweet singing transmits heart and compassion. They might be the least assuming vocal duo in pop music, but maybe the one that cuts the deepest. With the steady bolstering of the music around them, they convey large swaths of the human experience in these songs. It's the most real and approachable album they've done yet, hitting hard with one of the most joyful-sounding tracks they've done ("Check My Heart"); digging deep with the kind of searching, pastoral folk music that Nick Drake might have done if he were just coming up today ("Summer Rain"); and making the most heartbreakingly pretty music anyone is likely to hear anywhere ("Secret Music"). Slow Summits is an unhurried, understated masterpiece that should make fans of the band, and of music in general, glad that the Pastels have not only stuck with it for so long, but grown into the kind of group that could release something this warm and beautiful.