In the summer of 1994, when American alternative rock kids were kicking up mud to Nine Inch Nails and Green Day, “Dummy,” the debut album from the Bristol, U.K.-based group Portishead, rolled in like a moody fog.

While it was rooted in the hip-hop production techniques of sampling, scratching, crate-digging and loop-making, “Dummy” was a different mélange of vintage touchstones. The producer Geoff Barrow sampled a spy soundtrack by the polymath Lalo Schifrin; the guitarist Adrian Utley provided twangy counterpoint reminiscent of an Ennio Morricone score; and the singer Beth Gibbons crooned delicate, unsettling poetry fragments like torch songs. (The studio project’s lineup was rounded out by the engineer Dave McDonald.)

A quick and unexpected success, “Dummy” scored a Billboard Hot 100 single and MTV hit (“Sour Times”), was awarded the Mercury Music Prize and ultimately spawned a slew of imitators . The group became one of a handful associated with the sound writers called “trip-hop,” alongside Massive Attack and Tricky, acts that melded methodically slow breakbeats with murky atmospheres and floating melody. In a meta twist, “Dummy” itself became prime sample material for many ’90s rap producers, including Timbaland, Souls of Mischief’s Opio and the Arsonists’ Q-Unique. Its influence lives on today in the stylized vintage of Lana Del Rey and the murky beats of SoundCloud rap.

Portishead released a second album in 1997, then went on hiatus for a decade, returning in 2008 with “Third.” Today, Barrow drums for the brittle post-punk trio Beak> and is an in-demand soundtrack composer, while Utley is a session guitarist and releases music with his Guitar Orchestra and Gibbons can be heard on a version of Henryk Gorecki’s Symphony No. 3, recorded with the Polish National Radio Symphony Orchestra.