It's fitting that Diana Darby's fourth album is called IV (Intravenous), as this may be her most insular and intimate work yet. While she's been on a mission to make her music ever more minimalist since 2003's Fantasia Ball, on this set of songs she strips away as many barriers between herself and her listeners as she possibly can (if it's ever possible for music to be swallowed or injected, Darby's songs would be prime candidates), leaving little behind except her voice, guitar, and the occasional strings or piano. As on her previous albums, this uncompromising aesthetic is often riveting, particularly on the opening track, "Looking for Trouble," where the pauses between her fragile, whispery vocals are just as powerful as her actual singing, and on "The Alphabet," where Darby literally spells out love's pain in haunting terms ("Y is the question you ask yourself when you're alone") in front of a torchy backdrop of upright bass and piano. However, IV's spareness becomes somewhat frustrating in its middle stretch of songs, which are so delicate and sound so similar to each other that they tend to blur together; this is a shame, since tracks such as "Ugly Little Toad" feature some of Darby's sharpest lyrics: "If you had to live on truth you'd starve to death." The album fares better when there's a little more flesh around the songs' bones and blood, as on "Elena" and "Little One," where beguiling melodies balance Darby's insights. All in all, though, IV (Intravenous) is a welcome return from an artist who straddles alt-country, folk, and singer/songwriter territory with unique aplomb.