It’s Sheridan Smith season. Last month she played a grieving mother in the BBC drama Four Lives. Next Monday we’ll see her in ITV’s No Return, as a woman whose family holiday turns into a nightmare. And this week she stars in The Teacher, one of those dramas in which Channel 5 specialises: a premise that grabs you, a watchable star turn, and a plot so simple that your dog could follow it.

Smith brings a likeability to all of her characters, without hiding their flaws. Here she plays Jenna, who is a dedicated teacher – judging by her promotion to head of English at the beginning of the show – but an absolute shambles on every other account. She drinks to the point of blackout, turns up to school hungover in last night’s clothes, and insists on hanging out in clubs where she’s a decade older than everyone else.

She is also highly flirtatious, which is ropey enough when directed at her colleague (a shifty Kelvin Fletcher) but wildly unprofessional when applied to the teenage boys in her care. After one particularly drunken night out, she is arrested and accused of having sex with a 15-year-old pupil, Kyle (Ackley Bridge’s Samuel Bottomley) in a nightclub toilet.

You may remember a more elegant version of this story: Notes On a Scandal, a novel by Zoë Heller which was turned into a 2007 film starring Cate Blanchett and Dame Judi Dench. Blanchett’s character lived a bohemian existence in North London, while The Teacher is set in Bradford. Apparently, Channel 5 is most popular with Yorkshire viewers, which probably explains the setting. But, save for a couple of establishing shots, the show was actually filmed in Budapest, a fact that the director is forever trying to hide by only ever giving us partial shots of buildings and streets.

The script is by-numbers and doesn’t really merit four episodes (going out over four nights this week) but Smith goes at it with conviction. I’m not quite sure where this drama is going, though, because the question seems to be whether Jenna is guilty. She is protesting her innocence, and there is a grudge-bearing colleague lurking in the background so it could all be a set-up. But while Jenna remembers nothing of the night, viewers saw her up close with Kyle. Even if she committed no crime, would you let this woman near your teenage son? I’d recommend a change of profession.