Acoustic instruments and downy-soft vocals are Kathryn Williams' forte on Leave to Remain, her sixth release since 1999's breakthrough debut, Dog Leap Stairs. Like that first album, Leave rustles up the intimacy of Joni Mitchell's most private material, with Williams delivering her observations and confessions in a singsong whisper. The arrangements are sparser this time around; of the 16 guest musicians listed on the album sleeve, only a small handful play on any given track. Williams' accented alto and literate lyrics are kept at the forefront, which — given the strength of what she has to say, as well as the relative letdown of Leave's ornate predecessor, Over Fly Over — is a stealthily smart move. Is Leave to Remain a conscious allusion to Nick Drake's Five Leaves Left? It's hard to say, but Williams' continued comparisons to Drake are, as always, well deserved. She lingers over every melody, her voice hushed and humble as string sections and finger-plucked guitars bubble beneath her. The subdued style wears thin toward the disc's end, but several variations in volume — most notably the countryish semi-ballad "Hollow" — hold their own with Leave's stellar side A. Those who mistakenly categorize such material as coffeehouse music should pay closer attention to Williams' candid lyrics, which often pack more bite than an espresso. "We've been f*cking all afternoon, burning like fossil fuel," she sings on "Glass Bottom Boat," her subtle delivery contradicting such a supercharged line. But lest Williams' poetry be mistaken for something pointlessly vulgar, she immediately follows with what very well may be her most poignant lyric about love: "I feel like you've turned me into a glass-bottomed boat; you see everything I hide but still keep me afloat." It's this combination of wit and grit that gives Leave to Remain a delicate edge.