“Summer is obviously a time of release,” Florence Welch tells Apple Music. “But I think there’s an undercurrent of recklessness and memory that creates this kind of heartache.” The indie-rock shaman of Florence + the Machine has crafted an exclusive, transcendental mix that’s full of longing—whether it’s Elliott Smith’s aching poetry, Mitski’s edgy indie-pop or cuts from the Machine’s own Dance Fever.