This psychological thriller by Steven Soderbergh (“Side Effects” (2013)) has the distinction of being the first theatrical feature film shot almost entirely on iPhone cameras, and the result is impressive. Claire Foy (“Breathe” (2017)) plays Sawyer Valentini, a career-driven young woman who has just started a new job in a new city. We are invited to question her sense of reality when she becomes obsessed with the apparent stalking behaviour which is going on around her with her being the primary victim. When Sawyer is invited to spend a few days in a mental institution to rest and gather her wits, her apparent paranoia and delusions intensify. Soderbergh employs iPhone cameras very cleverly to both critique the provision of mental health help and to show Sawyer’s mounting psychological problems.