The first thing any clued-up time traveller would do when heading back a couple of decades would be to head down to the local newsagent and put a shed load on the winning lottery numbers.
But time-jumping Maggie (Marling) is cut from a different cloth (a hippy-drippy flakey shawl if you must know) and has a whole bunch of different priorites after landing in present-day LA from 2054.
She parks herself in a suburban basement, hires a couple of heavies and starts recruiting gullible beatniks into a survivalist cult while promising to guide them to safety from the coming apocalypse.
Word of the golden-tressed prophet reaches amateur sleuths Peter (Denham), a supply teacher, and his ex-model girlfriend Lorna (Vicius). They hit on the idea of infiltrating the select group and exposing Maggie as La La Land's answer to Derek Acorah.
Marling and co-writer and director Zal Batmangli's follow up 2011's Another Earth with a second slice of sci-fi without any sci-fi trappings: the nearest this gets to anything otherworldly is a weird indoor orchard and young Maggie insisting she drags an oxygen cylinder around with her.
It's a little bit po-faced with the whiff of student film school and is at its most rewarding when witnessing the disintegration of Peter and Lorna's slightly smug relationship courtesy of Maggie's cunning combination of scalpel-sharp cruelty and delicate empathy.
Marling is never a wholly convincing presence although early aspects of the film which appear initially risible - a barkingly complicated take on the high five among them - later show themselves to have a genuine purpose.
It's a small scale movie with some big ideas.