Ilove Unforgotten wholeheartedly. It’s the meat and two veg of television crime dramas. Every one of its four series so far has served up a rock-solid mystery, establishing a historical murder case and solving it within six tense, taut weeks. It may not have an HBO hiss at the start, or an A-lister in a leading role, but this is television to savour. Of course, the drama begins its fifth series under a giant cloud in the shape of Nicola Walker. It ended its last run by bumping off the much-loved gaffer, Cassie Stuart, killing her in a car crash after a bout of work-related burnout and exhaustion. Hers is such a big chair to fill that many thought the series would end for good, but the creator, Chris Lang, has chosen to continue, taking a grieving Sunny Khan (Sanjeev Bhaskar) into a Cassie-less future. Anyone worried that it wouldn’t survive the loss of Walker can breathe a sigh of relief. That’s not to say she isn’t missed, but Unforgotten has been around for long enough to know exactly what it is doing. It gets over the Cassie problem in two ways. First, it doesn’t write her out of the story. Everyone is still mourning her, particularly Sunny, who can barely make it home for dinner without popping to the cemetery for a quick chat at her graveside. Second, it doesn’t try to replace her with a like-for-like character. Sinéad Keenan plays the new DCI, Jessie James (for some reason, no one has yet mentioned that this is a funny name for a copper), and she is a standoffish tough nut who is all budget and no nonsense. And so to our cold case. During renovations of an old house in Hammersmith, the builders discover something hidden up the chimney. “Could it be a squirrel or a rat?” asks one of them, to which regular Unforgotten viewers might reply: try a very old human body that leaves a sprawling web of interconnected suspects spread out around the country, my friend! Naturally, given that he and Cassie have form for cracking historical cases wide open, Sunny gets the call, reluctantly inviting his new boss to the crime scene. From the off, it becomes clear that we’re not in Kansas any more. DCI James sniffs around, makes a couple of solid suggestions, then lays down the law. She wants them to stop focusing on historical cases in favour of more recent murders. Essentially, she wants to lead a show called Forgotten, in which long-buried victims of horrible crimes are left without justice for ever more. What would Cassie say? “We don’t live in an ideal world, do we? We live in a shitty one,” says Jessie, pointing out that they have barely enough time or resources to cover murders that happened this week. Unforgotten has always been good at showing the home lives behind the detective work; as Jessie’s first day on her new job has been spectacularly torpedoed by her husband casually letting her know that he has been having an affair, before nipping off to an overnight conference, you can understand why she might come across as a little chilly. But this is all about the body, how it got there and who is responsible. So far, like a good game of Cluedo, it lines up the suspects without telling us much about who they are, how they are connected and what they have to do with a body up a chimney in an old house in west London. So far, we have a wealthy aristocrat with what seems to be a social conscience; a petty criminal who funds his addiction by mugging women for handbags on the street; a formerly homeless chef at a small, successful restaurant in Bath; his partner, who is hiding at least one secret; and an Englishman working several jobs in Paris, who is lying to his mother about having a girlfriend. I can’t piece any of it together yet. I am happy not to try. The pleasure of Unforgotten is allowing yourself to be carried along by it, as it drops more and more breadcrumbs, leading you gradually to the end of the trail. Without Walker, it is a different trail, sure, but Sunny and Jessie have a lot to work through; I don’t doubt they will find some common ground in doing the job properly, whether leading by head (Jessie) or heart (Sunny). After all, if Bake Off can survive without Mel, Sue and Mary Berry, Unforgotten should be just fine.