Likewise, Maureen's relationship with her computer programmer boyfriend Gary (Ty Olwin) proceeds via Skype. She moves through her environment with ease, puttering about on her moped through the beautiful blue skies of Parisian afternoons. There's a lot of beauty in this world of dresses, ornaments, high-class apartments and first-class travel. Maureen is confident of her taste, friendly with the fashion designers and accomplished at her job. However, beneath the surface Maureen is troubled. Her twin brother Lewis died of a congenital heart condition which she shares. Add to this the fact that they were both mediums and Maureen is determined to contact Lewis for a sign. At first, she thinks this will be possible in his house where she detects a presence. The new owners - former friends of her brother - are also keen on Maureen exorcising the house before they move in. Unfortunately, the ghost appears to be another one and hostile to boot.
During a trip to London, Maureen begins to receive a series of mysterious texts messages from an unknown caller. What at first seems like a stalker entwines Maureen in a dangerous guessing game and the suggestion is that the spirit world might have caught up with technology. After all, "abstract photography was first done by spiritualists", comments a helpful YouTube video. With her head almost permanently bowed to look at her iPhone, Maureen is communicating constantly with another world that isn't really there. Assayas nimbly suggests that our distractions have the potential to haunt us as much as displeased spirits. However, as Personal Shopper progresses a rather predictable series of twists almost drain the story of interest. There are many moments that simply don't make sense and some elisions which might have been inept storytelling or might hide deeper alternative possibilities.
It would be impossible to expand on the above without some serious spoilers, so let's leave that there. Stewart, meanwhile, is wonderful. Her fidgety, sniffling, hair-touching persona infuriates some, but here it fits with the character and she's fantastic at projecting a "fuck you" insouciance and a fragility at exactly the same time - although during one particular extended scene someone really should have given her a tissue and told her to blow her nose. The belief in spiritualism is taken soberly and there are few sceptics in the movie: it's as similarly straight-faced as Clint Eastwood's Hereafter. Of course, it's all very daft and could shatter like a glass that has been held in the air by ghostly forces, but there's enough strangeness here to beguile the curious.
The 69th Cannes Film Festival takes place from 11-22 May 2016. Follow our coverage here.
John Bleasdale | @drjonty