"The Staircase (Mystery)" is the second single released by British rock band Siouxsie and the Banshees. Issued in the UK by Polydor Records in 1979, the track was written by Banshees members Siouxsie Sioux, Steven Severin, John McKay and Kenny Morris and produced by Nils Stevenson. The B-side of the single is a cover of the T. Rex song "20th Century Boy"
Although their debut album The Scream had already been released, "The Staircase (Mystery)" did not appear on it. Released as a stand-alone single, it became the group's second top 40 hit, peaking at number 24 in the UK singles chart. The track later surfaced on the singles compilation album Once Upon a Time: The Singles. When The Scream was remastered and re-issued in 2005 with bonus material, "The Staircase (Mystery)" was included in the package.