Good, starring David Tennant, needs more dosh spent on it. The former Doctor Who plays John, a literary academic living in Germany in 1933, whose cosy life is disrupted by troublesome females. His mum is a cranky basket case dying in hospital and his wife is a manic depressive who can’t look after their kids. Both women speak with Scottish accents. John has a fling with a third Scotswoman who studies Goethe at his university.

Weirdly, all three women – mum, wife and girlfriend – are played by the same actress. Couldn’t the producers fork out for a proper cast? They certainly didn’t spend more than a fiver on the set, which looks like an abandoned bomb shelter made of cardboard. The story follows John’s gradual drift towards Nazism which he embraces half-heartedly in the hope of furthering his career. His Jewish friend Maurice begs him for help fleeing Germany before he gets carted off to a death camp but John seems untroubled by his pal’s plight.

The story would have been more powerful if John’s mistress had been Maurice’s sister, but the playwright, C.P. Taylor, is an arid, ruminative type who shuns conflict or emotional depth. The show feels like a commentary on a play rather than a play in itself. Further budgetary problems spoil the second half when John goes to meet Adolf Eichmann who is impersonated by the same chap who plays the role of Maurice. Spare a thought for poor Elliot Levey, an excellent technical actor, who now has the name ‘Adolf Eichmann’ emblazoned on his CV.

It’s clear that the producers simply lacked the funds to stage this play professionally. Or did they? In the dying moments, seven extras appear dressed as Jewish captives and Nazi guards. So there was a proper cast lurking backstage all along but they weren’t allowed to take part. That’s no way to treat actors. They’re born to perform, to dazzle, to show off, to bask in the limelight. It’s cruel to make them spend two hours each night sitting in the dressing room begging their agents to find them a decent job. My son, a huge Doctor Who fan, was thrilled to see David Tennant on stage but he found the script disappointing. ‘I wasn’t expecting a play about Scottish Nazis,’ he said.

The Boy With Two Hearts opens in Kabul where Fariba, a married mother of three, makes a speech denouncing the Taliban. They order her to leave Afghanistan or to face execution. She clears off. This in itself seems strange. The death threat might easily have been lifted with the payment of a bribe but Fariba prefers to sell her house and to leave with her husband and sons in search of a nicer life. Their first stop is Moscow, where they spend six months living off funds provided by friends in Kabul. What a lovely jaunt for the family. Next they head to Germany, via Austria, and finally they reach Normandy, where they break into a truck and enter Britain illegally. Free healthcare is their goal: a family member has a dicky heart and the NHS will provide treatment without charge. That’s why they crossed the Channel rather than ending their journey in Germany or France.

There’s very little drama or heartache in this plodding yarn because the family have each other for emotional support and the troubles they face are minor. At one point they all squeeze into a car which feels a bit cramped. The back of their lorry is rather stuffy too. In Germany they’re forced to work by assembling pizza boxes, which is a bore but it’s hardly a life-changing crisis. In the course of their odyssey they discover the fate of less fortunate travellers. Money and valuables are taken by armed thieves. Females, especially little girls, are stolen from their guardians as a form of ‘tax’. One wonders what happens to these sex slaves. We don’t find out because the story wants to celebrate successful migrants who reach here with little hassle.

Several uncomfortable truths are concealed by this play. People in the Third World will never overthrow dictators while an easy route to the West exists. Policies that favour migration have created an intercontinental slave route, or trans-Asia rape trek, or whatever you want to call it, which governments and charities know all about. They use the word ‘compassion’ to describe their encouragement of sex traffickers, cut-throats and child abductors. This play is set in 2000 when it was still worth coming to the UK to avoid Islamist despots. But if Fariba had left Afghanistan last month and settled in Tower Hamlets (where this column is being written), she’d have found thousands of Muslim women walking the streets in the full-length body-robe that she protested against in Kabul. She might as well have stayed put.