Most recently seen on quite formidable, incendiary form in Jeff Nichols' Take Shelter, Michael Shannon plays Peter Evans, a drifter who claims to be a soldier, held by the military and experimented upon. Agnes (Judd) meanwhile has holed herself up in a crummy motel, her child's abduction and abusive husband's impending parole having turned her to a solitary, withdrawn existence fuelled by drugs and alcohol. It is into her world that Peter slips, introduced by a mutual friend, he begins to draw the susceptible Agnes into his destructive and paranoid delusion. Bug can be viewed at face value, as a study on mental illness and hysteria and where and how the two intersect, but it also has a wider more allegorical context. Peter's fears encompass government suspicion, fringe science, environmental conspiracy and media manipulation; Agnes' trauma has her spiralling downwards in a self-consuming depression. Sometimes it's hard to tell who's feeding from whom. Essentially a two-hander, Friedkin's horror may lack rotating heads or projectile vomit, but there's little doubting the film's white-knuckle intensity, in part due to the clever, claustrophobic set, and largely due to Shannon and Judd's seemingly abandoned willingness to descend into the mouth of madness to get the most out of these extraordinary characters.