The more incomprehensible and unsettling the real world gets, the more we welcome TV characters who make us feel safe. BBC One’s Cormoran Strike, a Cornish war veteran turned private investigator who operates out of a shabby Soho office, is reassurance personified. He’s a good man with sad eyes and a tragic past, the kind of TV detective you want to feed a shepherd’s pie and send away with a Tupperware full of leftovers. Everything about Strike, from his smoking habit to his hidden pain and carbs-n-booze diet, is a throwback to a different age. It’s not just the scratched cine film of Strike’s opening credits that speaks of nostalgia for the past, it’s the character’s crumpled, masculine solidity. Strike may be a returnee from a 21st century war, but his lonely takeaway nights in front of the TV and seedy London digs could be from any point in the last 50 years. Kind-hearted, tortured by his past, bad at looking after himself but committed to helping others, he’s a classic romantic hero. Think Sense & Sensibility’s Colonel Brandon with a glamorous provenance, a prosthetic leg and a reputation as an excellent shag. Even Strike’s will-they-won’t-they frisson with investigative partner Robin Ellacott is nostalgia in action. It’s such an old trick you wouldn’t think audiences would still fall for it, but down we topple. They’re both clever and likeable, each dealing with their own demons (him: a dead mother, absent rock star father and near-death experience in Helmand Province that lost him a leg, her: a violent campus assault by a serial rapist that caused her to drop out of university). We’ve seen versions of it all before, many times over, which is precisely what makes Strike comforting to watch. We know the drill. We know the stakes. And we know that, unlike in real life, by the end, evil will always be found out and punished. They’re the stars of four – soon to be five – detective novels by Robert Galbraith (aka J.K. Rowling). The first The Cuckoo’s Calling is set in the Hello Magazine world of supermodels, fashion designers and musicians. The second The Silkworm takes place in the rotten, back-stabbing heart of the UK literary publishing industry. The third Career of Evil is themed around misogyny and violence against women, and the fourth Lethal White looks at hypocrisy in both the politics of Westminster and radical activism. That though, is just plot. It’s the comforting sound of puzzle blocks gradually slotting together to form a satisfying shape. Strike’s real motor is Robin and Strike’s radiant and unexpressed love for one another. And it is love, not just the major hots. These two chime on a deeper level. Fundamentally, they’re both kind and capable and know right from wrong. They love their work and value the pursuit of justice over high salaries and chic living. They don’t just fancy the pants off each other; they respect and care about each other. It’s so vanilla, it’s almost a kink in itself. The fact that both of them glow like lightbulbs in each other’s company hasn’t escaped Robin’s childhood sweetheart and – since the surprise closing moments of series three – new husband Matthew. Unsurprisingly, Matthew’s no fan of Strike. He makes cracks about his missing leg and takes regular swipes at Robin’s less-than-extravagant salary. He also cheated on Robin while she was recovering from a serious, life-altering trauma with a colleague who definitely votes Tory. We don’t like Matthew, and we especially don’t like that he blocked Strike’s number from Robin’s phone at the end of Career of Evil. When she finds out, Robin won’t like that either. Strike has an ex from his university days (Oxford, but he dropped out to join the army after his supermodel mum died of a heroin overdose – administered, he’s always suspected, by his reprehensible musician stepdad played by Super Hans from Peep Show). His break-up from socialite Charlotte Chapman (Natasha O’Keeffe) is what found him crashing at his Denmark Street office in series one to three. Their history is sketchy but through flashbacks we learn something about a lost pregnancy and doubts over the identity of the father. Charlotte is now married to a man named Jago but, having taken the trouble to post her wedding photos to Strike, is clearly not over him. Were Strike and Robin ever to give in to what their hearts want and work off all their sexual tension over the course of a decades-long relationship filled with thoughtful gift-giving and romantic perp chases in Robin’s Land Rover, buoyed up by the everlasting gratitude of all the people their work has helped, the whole show would spin off its axle and bounce away. Fans desire it, yet we resist it. It’s an eternal – and comfortingly familiar – dilemma. Just the distraction we need. Four-part series Strike: Lethal White starts on Sunday the 30th of August at 9pm on BBC One. The previous series are available to stream on BBC iPlayer.