Sheridan Smith stars as an ordinary mum caught between two contrasting worlds - the everyday grind of suburban life and the high-risk game of insider trading - in this moving, funny and characterful drama. Office cleaner Sam (Sheridan Smith), one of an invisible army working every night in London's financial centre, dreams of a better life. But, struggling with an online gambling addiction, she's going under. One night, hidden in plain sight, she overhears an illegal trade being made. This lucrative stock market information could be the break she needs. Armed with a copy of 'Trading for Dummies' and her gambler's nerve, Sam has everything and nothing to lose - but how far will she go to turn her fortunes around?