One of the biggest advantages of streaming is discovering hidden gems that allow you to see familiar names in a whole new light. Smaller (and sometimes stranger) films made by high-profile actors or directors (often earlier in their careers) can offer us greater insight into their body of work, or change our understanding of what they're capable of as artists. Yorgos Lanthimos's 2017 The Killing of a Sacred Deer, which recently arrived on HBO Max, is a perfect example of this kind of film. Before he became a regular Oscar nominee with the likes of The Favorite, Poor Things, and Bugonia, Lanthimos released this modern Greek tragedy — only his second English-language film, following 2015's The Lobster. A fever dream of jagged morality and escalating consequences, The Killing of a Sacred Deer also produced one of star Colin Farrell’s finest performances, and introduced an emerging must-see performer in the form of a young Barry Keoghan, What happens when a man who is used to being totally in control is presented with an impossible choice? That’s the nightmare at the center of The Killing of a Sacred Deer. Keoghan plays Martin, a precocious teenager who enters the life of Steven (Farrell), the heart surgeon who tried, and failed, to save his father’s life. Initially, the pair become friends, with Martin befriending Steven’s family, as well as receiving guidance from him. However, this bond takes a sinister turn when Steven’s attention becomes harder to obtain, and Martin unveils a terrifying ultimatum: He tells Steven that if he does not kill one of his children or his wife (Nicole Kidman), they will all begin to suffer unexplained ailments and die. Paralyzed by guilt, Steven watches in horror as his agitator’s predictions come true, pushing the doctor toward a choice no one could possibly dream of making. One of Lanthimos’ best works once again unpicks morality and observes dispassionately as his characters are driven to extremes. What is startling about this is how he also brings out unexpected performances from his cast. When you think of Colin Farrell’s best performances, they're all infused with his signature wit and charm: an impatient hitman in In Bruges, a pure soul turned vengeful in The Banshees of Inisherin, or a streetwise villain in The Penguin. While his repertoire is varied, he's typically lit up the screen with roles that portrayed the light and dark sides of the human condition. But with Steven, he stripped all that away, playing someone hollow, calculating, and ruthless. Farrell had certainly played within Lanthimos’ world before, experimenting with awkward line delivery and semi-surreal humor of The Lobster. However, he is far more vulnerable in that role. As Deer's Steven, the stilted scenes lead not toward absurdism, but display someone devoid of feeling. The things that make Steven an excellent surgeon have seeped into his every pore, as he treats people in his personal life like patients he’s keen to get off of his to-do list (he even role-plays sedation in the bedroom with his wife). When faced with his own wrongdoing, he reacts passively, as if all that is happening to him is hypothetical. That disconnect between his intellect and emotions raises the stakes as the film moves towards its nightmarish conclusion: Steven treats his own suffering children as if they were strangers, and asks their school principal who is “better” in order to make the decision easier. It’s an engrossing performance that allows Farrell to show a side of his abilities we haven’t seen before, where the absence of emotion becomes the most chilling aspect of who he is on-screen. Future Oscar nominee Barry Keoghan was still relatively unknown when he took on the role of Martin, but after the release of Lanthimos’ film, it became clear that he was an actor to watch. As jarring as it was to watch Farrell’s uncaring caregiver in action, it was equally disturbing to watch Keoghan's curious, unguarded teenager reveal himself to actually be sinister and unforgiving. The character uses his perceived innocence to work his way into the lives of his targets, then unveils a horrifying plan, wrapped in a matter-of-fact delivery that makes your blood run cold. Despite being 17 years Farrell’s junior — as well as a far less experienced performer than his fellow Irishman — Keoghan held his own with the veteran in a way that few actors his age would manage. His performance would herald his arrival on the big screen, and lead him to take on other scheming roles, such as Saltburn’s Oliver Quick or Duke in Peaky Blinders: The Immortal Man. As he stepped into Lanthimos’ deliciously twisted world, a new star was born. Almost a decade from its release, The Killing of a Sacred Deer remains fresh, intriguing, and unforgettable. A must-watch for fans of Lanthimos' work, it's a chance to see both the director and stars in a more cerebral, thrilling setting.