Green’s Dictionary of Slang

a swindle, a fraud, a confidence trick.

1914		Jackson & Hellyer Vocab. Criminal Sl. 34: flim [...] Current in polite criminal circles. A swindle; a fraud.
1925		Flynn’s 25 July n.p.: The flim is a hoary trick, but generally works.
2001		(con. 1975–6) E. Little Steel Toes 171: I’d like to experience something other than flims and flams, robberies and scams.