The Replacement was born from the very real anxieties that some women may feel as they take a break from working to have children. It then ups the ante by turning these fears into a reality.

As if it were almost ripped from the Hitchcock playbook, it toys with tension and is guaranteed to turn your knuckles white.

Ellen (Morven Christie) and hubby Ian (Outlander's Richard Rankin).

Ellen (Morven Christie) is a successful architect on the top of her game. She has just landed a multi-million dollar project that is about to turn soil and has promotion set firmly in her sights. Ellen suddenly finds herself having to think about putting her plans on hold due to a surprise, but welcome, pregnancy.

Paula (Vicky McClure) is Ellen's maternity cover.

Enter Paula (Vicky McClure), a mum of 10 years looking to return to full time work. 

She's perfect. 

She's switched on, eager to please and above all else, she's been exactly where Ellen is now. The situation couldn't be better, Ellen feels safe in handing things over to Paula until she returns. She insists the firm hire her as maternity cover. 

The dialogue between Ellen and Paula may seem fine on the surface, but something just isn't right...

All seems to be right at first, but it isn't long before Paula's behaviour starts to make Ellen feel uneasy.

Paula's been meeting with the clients behind Ellen's back, and is suggesting changes to the project's design. Plus Paula's obsession with her pregnancy is getting creepy. 

Ellen voices her concerns, but everyone assures her that she's not being replaced...

The Replacement starts its three week run on Sunday 20 August at 8.30pm on TVNZ 1.

All three episodes will be available to be streamed right here from Sunday night (just in case you can't stop at one episode).