Sam is a struggling mum with an online gambling addiction, desperately trying to keep her life together after separating from her husband. With her ex, Dave, threatening to take her daughters away, Sam wants to prove she’s a dependable parent to her two daughters, Alice and Lily. But getting back on track looks impossible for Sam with spiralling debts and having to a work zero-hour contract on the minimum wage as a cleaner in Canary Wharf making Sam’s life is thrown into disarray when she discovers access to lucrative and illegal stock market information at the office she cleans. Realising this could be the answer to her prayers, Sam starts delving into the high-stakes world of the stock market. Persuading her best friend Jess to come in on the secret, the two cleaners start to navigate dangerous new territory.

Sam's money-making plan starts to bear fruit, but it comes at a great cost. Frustrated by her mum's constant absence and the new lodger living in her bedroom, Alice seeks refuge at her dad's house. Later, Sam's listening device is found in the office, and an investigation is launched which cuts off their source of information. Desperate to make amends with Jess and bring in some money, Sam follows an inside lead and enlists the help of a fellow cleaner, Mina, to execute a risky scam in another office.

After a pivotal discovery, Sam takes an enormous risk and makes contact with 'Swanny' but finds herself getting in far deeper with him than she bargained for.

Determined to prove she can fill Blake's shoes, Sam is given the impossible task of acquiring secret information about an upcoming property deal.

Sam and Swanny grow closer and he entrusts her to make a large investment for him. Seduced by his glamorous and risky world, she goes to desperate lengths to pull off the task.

With Swanny on her back desperate for his money, Sam's world falls apart when her landlady returns with some devastating news.