Jason Bailey’s review published on Letterboxd:
Delpy’s fifth feature film – and her first in her native French – tells the story of a single mom (Delpy) and the kind man (Bon) she falls for while on a spa vacation. Delpy seems to set up a story of the complications of an urbane she and a provincial he making it work, and then she introduces the title character (Lacoste): the woman’s teenage son, whose subversion of the relationship first seems a charming affectation (playing out like a French 'Cyrus,' perhaps) and then reveals him to be a genuine monster, bent on sabotage and destruction. Much of the second half is watching the tumblers of disaster fall into place, teeing up a total meltdown of this poor sap’s personal and professional life, and not all viewers enjoy that kind of slow-motion car wreck. But you’ve got to give Delpy this: there’s something wonderfully gleeful about her willingness to tug that thread until the whole sweater unravels.