Playwrights can’t go too far wrong with a contested legacy. When wealth passes from one generation to the next and there is some sort of problem, you have a conspiracy. The legacy (Channel 5) are fighting on a good wicket, with everything to play for. And then the characters open their mouths.

The widowed patriarch whose fortune is at stake is Dennis (Larry Lamb). Among her three adult children, Daniel (Robert James-Collier) is having financial problems with his restaurant, Sian (Gaynor Faye) is a single mother who is having bad luck on dating apps, and Chloe (Jemima Rooper) is married but there are hints, thinly veiled, of a dark secret. When Dennis collapses, the children put aside the mourning to get into the intrigue of bickering and feathering the nest.

Top actors can only do so much with sluggish writing. Some of the cheap, joyless dialogue even has the raw roughness of improvisation. “I’m sure Dad took care of us,” one of the women says with such a wry sound before the contents of the will are revealed to leave everything to a mysterious second wife.

In it, she appears as Samantha Bond in panto villain mode, all nastiness and sullen coldness. We also get the chance to meet her ex-husband, played with a wild look by Kevin Whately, who has barely worked since Lewis ended in 2015 and must have had a very empty schedule to leave the house for this. His character, briefly seen and very angry, doesn’t just call a spade a spade; he uses one too, just so you know.

Legacy has one of those plots where none of the characters seem to know anything about the others. So the revelations come as regularly as the commercial breaks, and the twists and turns are visible from space. A deadly bottle of Poteen discovered in a cupboard. A loan shark who might as well sport horns and a curly tail. An 11th hour police intervention at the cremation. The writer is Aschlin Ditta, whose most recent credit is an episode of Queen of Oz. Before that, he wrote Swim with the men, a star-studded but limp comedy about midlife sync. This, alas, is another lead.