Siblings Dwight (Patrick Fugit) and Jessie (Ingrid Sophie Schram) have somehow wound up with a large, depressing family home and the endless chore of being carers for their younger brother Thomas (Owen Campbell) – a frail, androgynous, lank-haired youth who subsists on human blood and can’t expose his skin to daylight. This is one of those films that can’t bring itself to use the word ‘vampire’ – imagine if no one in Jaws was allowed to say ‘shark’ – but also doesn’t have any truck with, say, ‘porphyria’. Thomas must have a medical rather than a supernatural condition, if only because the tone of writer-director Jonathan Cuartas’ film is so resolutely practical and unmagical. But, here, vampirism is very much a stand-in for family ties that can strangle.
Dwight, bearded and slightly paunchy, is edging into middle-age. He has to go out and abduct homeless nobodies to be killed and bled to feed his brother … while Jessie, the family breadwinner thanks to her gig as an unsmiling waitress, notices Dwight has been seeing a hooker (Katie Preston) and – out of jealousy or a need to rein in her partner – decides the woman ought to be the next unwilling blood donor. Dwight is more interested in talking to the prostitute than having sex with her and is so lonely he even keeps a victim (Moises Tovar) alive to have someone to vent to – though the guy doesn’t speak English, so Dwight doesn’t pick up that the photo in his wallet is not a beloved son but the stateside connection who was supposed to help the illegal in America but hasn’t shown up. Even as the film finds time for external connections, we’re mostly in the drab house with the trio – and there are obvious parallels with many carers’ tales of suffering and sacrifice, simmering resentment against an afflicted relative who is at once pathetic and monstrous.
Dwight and Jessie try to give the adolescent Thomas an extended childhood – with karaoke sessions, Christmas every month, home-school math and a kind of weary attention to every tantrum and impulse. Thomas hears teenagers outside on the street and longs for friends, though bringing any person into the house is bound to lead to disaster – which duly makes for a flurry of action after a long, contemplative stretch. As things escalate, there’s a creepy sense Dwight can see a way out of his bind if Thomas learns to look after himself by hunting humans, but that would mean becoming a full-on neck-biting monster. My Heart Can’t Beat Unless You Tell It To is a dour film – sparser and less gothic even than Martin, Habit, The Addiction or The Transmigration – with buttoned-down, affecting performances and a sense of trap or stasis that makes for gloom rather than dread. Most ‘realistic’ vampire movies treat human blood like a drug, but here it’s just gruel – a survival food – and the most upsetting moments come when the thick gore is spilled or wasted, as Dwight and Jessie feel the weight of what they have to do to keep it coming to the table.