Eureka Day is a topical satire set in a woke school in America. An outbreak of mumps has led to calls for a vaccination programme that will prevent the school from being quarantined and shut down entirely. The script, written in 2018, has acquired new layers of meaning since the Covid terror. It opens with a playful sketch in which four white teachers and a black parent try to agree how many ethnic categories should be recognised by school officials. Their friendly conversation conceals a toxic seam of racial suspicion and hostility. The writer, Jonathan Spector, is probably a rock-sold liberal who wants the world to know that the woke cult has gone too far. The play’s highlight is a 20-minute passage of comedy which reaches a peak of hilarity that would make Oscar Wilde envious. It’s that good. There wasn’t a soul in the theatre not convulsed with laughter.

The scene involves a live-streamed debate about the vaccination policy. Some parents view the jab as a safeguard, others see it as a threat to their kids’ health. During the discussion, their online comments are flashed up on a wall behind the actors’ heads. At first the mood is co-operative and welcoming. Then the temperature rises and a few insults are traded. Some parents offer scientific theories that are challenged by other parents with better theories. The atmosphere thickens. Gentle sarcasm gives way to angry abuse. Inevitably someone makes a reference to Hitler, which elicits a retort. ‘We have a winner! First mention of the Nazis.’ The language descends into the gutter and the parents issue foul threats against the kids of other parents. In a few spare minutes, a friendly conversation has turned into a savage, murderous dispute.

It is a shockingly beautiful piece of writing. And the audience responded with something more complicated than ordinary laughter. There was relief too, and gratitude. At last, we thought, someone has seen what’s going on and spoken out. Oddly, the scene strengthened our sense of fellow-feeling because it bound us together in recognition of our common frailties. Which of us has not played the Hitler card to win an argument? After this, the play fails to reach the same comic heights a second time, and there’s a faint sense of anti-climax in the second half. Still, this is an inexpensive production with a smallish cast and a cheap but good-looking set. Surely it’s heading across the river.

The Clinic is a classic yarn about an outsider who sweeps into a happy family and creates havoc. The first act drags a little as we meet the characters and get attuned to the family dynamic. They’re prosperous, successful types living in a £2 million London townhouse. Dad writes popular psychology books and Mum volunteers at a women’s shelter. The son is a police officer married to a Labour MP and the daughter is a grumpy medic who hates the NHS.

It’s fun to watch them bickering and taunting each other because they’re amazingly rude and tactless. The parents ask their son’s wife if she’s pregnant. (Which is taboo, surely?) And Dad informs his daughter that her mood swings are probably caused by ‘man problems’. Then the outsider arrives. She’s a single mum in financial trouble, and the family take pity on her, condescendingly, and offer her free accommodation. At first she resents the wealth and success of her saviours. And when she learns that the parents are ‘Tory voters’ she spits the phrase out as if it were synonymous with ‘members of the Waffen SS’. But she gets used to middle-class life. There are no bills to pay. And Mum is willing to care for her baby around the clock. Dad, who leers at her suggestively, proposes that they work together on ‘his next project’, which turns out to be seduction. The kids begin to resent her as she threatens to replace them in their parents’ affections. And Dad’s affair becomes increasingly hard to conceal. She may even be carrying his child.

These horrible tensions erupt volcanically during a traditional game of Lotto at Christmas. This creates an exquisite counterpoint between the bland procedures of the game and the explosive arguments sweeping around the table. Chekhov couldn’t have conceived the scene better.

There’s a strong cast led by Donna Berlin who gives a sensationally warm and funny performance as Mum. She’s the star. However, the box office hasn’t exactly caught fire. Poor marketing is to blame. The author, Dipo Baruwa-Etti, has chosen a title that fails to describe the play’s tone and content. And the imagery on the Almeida’s website suggests that the play is a dour traditional folk tale steeped in woe and shame. Come on, chaps. If you’re promoting a show full of laughs, say so.