Fiona Apple’s “The Idler Wheel...” is not a sing-along album. Her piano chords are full of dissonance, her melodies are rhythmically off-beat and staggered, and her intonation is wholly unexpected. It is clear that Apple has come a long way musically from the brash ’90s earworm “Criminal” that kicked off her career. Fifteen years later, Apple has ditched her bluesy, alternative rock and developed a grittier, discordant palette. With its unique instrumentation and spirited, self-reflecting lyrics, “The Idler Wheel” signals a more experimental and darker stage in Apple’s musical development.

The album’s seriousness is evident from the fact that every song is in a minor key. Apple not only acknowledges the emotional darkness, but embraces it: “Nothing wrong when a song ends in the minor key,” she sings in “Werewolf.” The music is not supposed to be easygoing and upbeat; rather, through this album Apple seems come to terms with a glum state of mind, alleviating it with bursts of energetic trebles and positivity that create a breathtaking, frantic, and constantly shifting whole.

This state of mind can be seen in the lead single, “Every Single Night,” a welcome return for the long-inactive artist. The juxtaposition of playful chimes and Apple’s powerful, earthy vocals creates a dream-like sound that is all at once eerie and infectiously quirky. The simplicity of the chimes and minor piano chords allows for the artist’s throaty voice to dominate the recording.

Apple’s vocals lend power to the emotional, turbulent lyrics on the “The Idler Wheel...” While Apple mastered the love song on previous projects, her lyrics on the new album focus more on her quest to abate her inner turmoil. “Now I’m hard, too hard to know / I don’t cry when I’m sad anymore, no no,” sings Apple in “Left Alone.” “Tears calcify in my tummy / Fears coincide with tow.” The lyrics allude to a newfound strength that is reflected in the sinewy roughness of the instrumentation.

Apple sounds fierce even on the album’s only love song, “Anything We Want.” The song mixes Apple’s distinct wail with light percussion and heavy piano chords, and its raw passion makes it the climax of the album. “We try not to let those bastards get us down / We don’t worry anymore cause we know when the guff comes we get brave,” she sings. This statement of purpose emerges from the cacophony of rumbling snare drums to coalesce into a powerful chorus that reveals Apple’s impressive command over her music.

The biting power that is manifested in “Anything We Want” winds down into “Hot Knife,” the final track of the album. The shift into “Hot Knife” is a refreshing one—whereas Apple’s work in the first nine tracks of the album is heavy and slightly cold with melancholy, the final song is lighter and hot with innuendo. Performed as a duet between Apple and her sister Maude Maggart, “Hot Knife” is foot-tapping perfection in canon-like harmony. Apple’s exclamatory solos frequently cut through the ethereal, multi-layered chorus, providing an interesting dialogue between sensual and sharp vocals.

Despite the soothing mellowness of “Hot Knife,” “The Idler Wheel” is ultimately characterized by an untamed ferocity. “I may need a chaperone,” Apple states in “Daredevil.” She seems conscious of the fact that her music is challenging and alienating, yet she refuses to compromise with her artistic vision.

—Staff writer Jihyun Ro can be reached at jihyunro@college.harvard.edu.