Costume suggestion:
🕵️Fashion of the time for ladies was flapper dresses with uneven hemlines and low-heeled button-strap shoes, along with cloche hats and lots of jewellery.
🕵️♂️For the men it was suave 1920s suits with a smart pair of spats, a straw Panama hat or boater, round metal-framed glasses, braces and loafers. Think Great Gatsby, Boardwalk Empire and The House of Elliot.
Don't worry if you can't find anything, although best dressed will be announced at the end of night!