This new fast-moving drama series starring Morwen Christie (The A Word) and Vicky McClure (Line of Duty) promises to be a roller-coaster ride from start to finish as writer/director Joe Ahearne keeps viewers gripped to their TV sets over the next three weeks.

At the top of her career, Ellen, (Morwen Christie) falls pregnant. She works as a designer for a firm of architects where she lands an important contract for a new library. When she discovers she is pregnant, her ‘replacement’ for maternity leave appears.  Enter the polished Paula (Vicky McClure), confident, radiant, and eager to begin her new role.  All appears to be well as Ellen had only planned to be off work for a few months. After the interview, Paula was hired.

Despite an early start, it appears that Paula has an agenda of her own. Discussions with company clients take place without Ellen’s knowledge whilst confident and pushy Paula appears to be highly regarded by the office.  Her unhealthy interest in Ellen’s pregnancy becomes a step too far, so Ellen insists Paula “stops cutting me out of conversations with my clients”.

Ellen suggests to her PA “copy me in on everything meaningful” after discovering that Paula appears to be making suggestions about work, suspecting that she is ‘taking over’ her role before Ellen goes on leave.

Meanwhile, Paula decides that it may be convenient to have Ellen out of her way altogether, so during a site visit when Ellen falls, Paula wants to report the incident despite Ellen begging her not to. Ellen fears this will lead to her early dismissal.  The scene showing Paula’s expression on her face whilst Ellen ‘feels the tiles’ on the floor in bare feet, suggests that perhaps she has ulterior motives before the fall took place?

Paula takes on Ellen’s library presentation and unsurprisingly makes a success of it. Her audience is captivated and the expected applause follows.   Ellen realises that by giving Paula the reins, the horse has bolted before the stable door has opened!

Ellen’s relationship with her partner (who we learn was her psychiatrist in the past) starts to show cracks. In the scene of her first scan, the baby’s sex is not identified, but then later in another scan when on her own, the sex of the child appears to be female.

Final action scenes take place in the dark on the building site with hard hats and a dodgy key code access system. This makes atmospheric suspense camera shots, but not plausible these days where health and safety rules, especially concerning building sites. Admittedly, without them, the plot wouldn’t work.

The finale leaves viewers wishing next week’s Episode 2 would come sooner rather than later. As a body falls from the ceiling of the construction site after a ‘phone call from Ellen’s boss urgently needing her to meet up on site, the audience is left thinking was she about to reveal all before her doomed departure?  Also, it looks like Ellen is in premature labour?

What a cliffhanger!

Aired at 9pm on Tuesday 28 February 2017 on BBC One.

What did you think of this week’s episode? Let us know below…

Reviewed by Zoé Patrick.