Teenage girls are scary at the best of times. But Billie Eilish takes it to a whole new level. Just take a gander at the cover pic of the 17-year-old L.A. pop phenom’s debut album: Decked out in institutional white T-shirt and sweats, she’s perched on the edge of a bed, grinning maniacally and leering through pupil-less eyes like something out of a Japanese horror movie. It’s enough to give you the creeps. And to her credit, the rest of When We All Fall Asleep, Where Do We Go? is just as nightmarish and weird. Co-written and produced with her brother Finneas O’Connell — and reportedly inspired by her own twisted dreams and night terrors — this demented 14-song groundbreaker eschews the usual lowest-common-denominator dance-pop fluff for idiosyncratic, introspective and intriguingly inventive songcraft and sonics. Eilish’s multi-tracked, intermittently treated vocals emerge conspiratorially hushed or gothically spidery, sounding more like reluctant confessions than entertainment. Her brooding lyrics are obsessed with death and drugs, sex and suicide, heaven and hell, violence and violation — and other grisly topics beyond her years. (Typical couplet: “I like the way they all scream / Tell me which one is worse / Living or dying first / Sleeping inside a hearse.”) Her songs are edgy, minimalist electro-pop creations that are usually anchored by subterranean speaker-rattling bass blasts and topped with little more than fingersnaps, throbbing synthesizers and spooky tinkling pianos. It is easily one of the oddest and most unsettling major-label pop albums to arrive in recent times. Which also makes it one of the most interesting and memorable pop albums in recent times. Yeah, she’s scary. But a lot of the time, she’s also scary good. Keep your eyes peeled.