“I made a new life for myself from flowers,” marvels the green-thumbed Narvel Roth. “How unexpected is that?” To be fair, it’s about the only plausible thing that happens in Paul Schrader’s Venice Film Festival out of competition entry Master Gardener, an incredibly silly but fitfully entertaining noir-tinged drama that follows so neatly on from First Reformed and The Card Counter that it’s almost as if Schrader has patented his own sui generis subgenre, a mix of the sublime and the ridiculous that just about works if you’re prepared to walk the line with it.