Bal Masque (1995)

The tag line on this game is "A Game to Catch a Thief".
The players control a couple of dozen characters at a masked ball, moving around the dance floor - one character is the 'thief'. Players gradually gain information through movement around the dance floor and into and out of the adjoining rooms, and through the actions proscribed by the large number of cards. One player is designated "One Who Knows" and has special powers (an extra card deck).
There are clear parallels with Clue/Cluedo here, but with quite different (and more complex) turn mechanics.
Although designated 2-6 players, it's really designed for 4 players, with variant rules provided for 2,3,5 and 6 players.
Contents: Average sized board with ballroom design; 24 character pieces (5cm high card-in-stand figures) and correspondingly 24 Suspect cards; 121 Harlequin cards (actions); 21 Clue cards; 5 Thief cards; 11 "One Who Knows" cards; and two dice. There are 60 plastic diamonds for use as currency.
The rules have a fantasy theme to them. To quote: "Bal Masque is a game, within a game, within a game, an elusive glimpse of far horizons. As Bal Masque unrolls it's magic carpet of pleasures, players find they have crossed the invisible threshold of NOW into the elegant and eerious, incredibly, fantastic world of Bal Masque".