Fast Labour, West Yorkshire Playhouse, Leeds

In a court case reported in this paper in 2005, a Ukrainian asylum-seeker called Victor Solomka was accused of making millions of pounds in three years off the backs of hundreds of illegal immigrants from Eastern Europe. As one of Britain's biggest and most ruthless gangmasters, exploiting a market where factories are desperate for casual labourers, Solomka was convicted and is currently serving a prison sentence, after which he will be deported back to the Ukraine.

He might be surprised to learn that Steve Waters has created a fascinating play around his transition from impoverished new arrival in the UK to kingpin in a lucrative regime that was built on fear and false documents.

Waters, himself the son of economic migrants, has woven several authentic details into his drama, including a Ukrainian central character called Victor, a bullish Russian-Moldovan henchman, and a company called Fast Labour.

But where fact and fiction blur is less important than the impact of the writing itself and the coolly discursive attitude Waters brings to a hot topic. At first we even feel pity for the bruised and threadbare Victor begging for work in non-existent English. The affluent gangmaster pleads on his behalf. His papers are in preparation. In the Scottish fish-processing plant somewhere north of the granite city, Victor is allowed to work, filleting raw fish. He could be forgiven for feeling gutted himself – but not crafty Victor. Well-played by Craig Kelly in a focused performance, Victor sees how he could use his experience in a factory back home to set up his own employment agency.

The story unfolds, chronicling his rise to power, supplying an illegal workforce of staggering numbers from Russia, the Ukraine, Latvia, Moldova and Lithuania to food-factories and farms across the country. Forged documentation and fake rubber-stamps play their part along with two trusty lieutenants and the feisty Scottish personnel officer who gives him his first break. She's a stickler for employment law but such are Victor's charms that she chooses to turn a blind eye to the realities of how his business is developing. In an assured and promising debut, Kirsty Stuart builds on her role as someone with a confused moral code and a curiously detached involvement in shady affairs.

The foreign characters may seem stereotypical – Joseph Kloska as an earnest Lithuanian and Roger Evans as the dim-witted, right-hand man – but their nationalistic prickliness rings uncomfortably true. Ian Brown's fast-moving and compelling production handles the change of scenes seamlessly, with the help of ingenious video projections that whizz us up and down the M1.

In the third act, in Victor's hastily-built mansion, his wife having reluctantly joined him, events take a strange turn. The unscrupulous English gangmaster whom Victor duped and now competes against, turns up, proving his upper hand with his county and government connections. You just know that, with his comfortable middle-class home within spitting distance of Ely Cathedral, he's a Tory voter. Mark Jax brings an appropriately bland satisfaction to the role of the glove-fisted manipulator playing the system. Yet, when a devastating tragedy occurs, it is difficult, in the way it is presented here, to feel the sense of shock such an event would normally provoke.

Feelings spiral out of control, fuelled less by vodka than by class and racial divide and pride, and, towards the play's end, Victor's attitude and his swift exit seem out of character with both the true case that inspired the play and his own character within the drama. It's a testament to Waters's confidence in his theme, however, that characters come across vividly and, in the style in which he considers his topical subject, there is never a hint of tedium.

To 17 May (01113 213 7700)Hampstead Theatre 30 May to 21 June (020-7722 9301)