The BBC1 drama The Replacement can be summed up in three words: gripping and tense. Writer and Director Joe Ahearne has created a simmering pot of suspicion that makes for a fabulously enjoyable three hours of television. It weaves a fantastic web of intrigue and doubt as pregnant mum Ellen (played by Morven Christie) suspects that not is all as it seems with Paula (Vicky McClure), the person drafted in to cover her maternity leave.

Throughout the first hour, the camera is used to good effect. The many close-ups note the subtleties in Ellen’s movement and expression as Paula begins to get under her skin. When it zooms in, from the point-of-view of Ellen, on Paula, it causes us to suspect McClure’s overly-friendly character. The panning shots are especially effective in the storytelling, their slow movements across the scene to the accompanying soundtrack, with its sinister tones, conveying a real sense of dark mystery.

As the drama moves on, the questions only keep coming. Ahearne manages to keep the viewer guessing right up to the third episode, when things take a far more sinister turn. Both Christie and McClure come into their own here, although they are excellent throughout as the two lead characters. Christie plays emotional vulnerability well; McClure’s stare is disturbingly vacant. As the titles suggest, this has something of a classic Agatha Christie mystery about it. It is testament to the quality of the writing that I found myself swaying between the two women, suspicious of either one or the other, changing my mind throughout.

The only disappointment to this otherwise excellent three-parter was its ending. It felt incredibly rushed; the loose ends were tied up in seconds. It was as if it had originally been four episodes that, at the last minute, had been cut to three. But otherwise, this was a gripping drama, reminiscent of Doctor Foster in terms of its slow burning apprehension, revealing close-ups and foreboding soundtrack.

It’s a pity it ended rather abruptly. But in terms of the BBC’s offering so far in 2017, it is certainly up at the top for entertaining and enjoyable drama.