The shifting timeline of Doctor Foster episode 4 – explained

The time-frames and how Gemma's plot came together

The episode began at 8am on a Wednesday with Kate receiving an envelope containing Simon's tie. He wriggled free from her accusations, but his new wife looked unconvinced, opening a drawer and perusing the package Gemma had handed her at the wedding party in episode one (Simon's speech from his first wedding, apparently).

It's from this moment that Gemma's intricate plan played out – she had her friend Carly (more on her below) bump into Kate to plant doubts in her mind, before later arranging for her colleague Sian to let slip that Simon's old house was now on the market.

Kate, of course, could not resist hunting for more evidence – especially after finding the photo of Gemma on Simon's phone – and waiting for her at the 'For Sale' house was a) Gemma's new address, written in multiple locations to be sure it was found, and b) neighbour Anna who delivered her own account of Simon and Gemma's aggressive sexual reunion. The estate agent was tipped for his role in the business and Kate was on her way to the hotel where she found Gemma... and – to her surprise – her young daughter Amelie.

It's at this point, we hauled back to 8am the same morning with Kate's mum, Susie, receiving a text from Gemma asking her to meet. She went along where Gemma presumably convinced her about her night of passion with Simon.

Switch scene to Simon's office where he received a phonecall from his ex-wife threatening to "destroy everything". It's a call that was made from the hotel where – as we then saw – Gemma was based with Amelie, Kate's parents, and now... Kate.

We'd caught up with the earlier timeframe.

Except Gemma's grand plan didn't work as she'd hoped. Kate pretended she knew about Simon's infidelity and marched off home where she confronted her husband and got him to admit his misdemeanours.

But Simon's confession didn't sit right and Kate made a late-night visit to Gemma's hotel before the doctor drove the pair of them back to Parminster and finally convinced her to ditch her cheating spouse once and for all.

We then jumped forward to the next day where Simon was struggling to access his bank account. His suspicions were raised further when he found out Kate's godfather Mark wasn't at work and – upon getting a text from wife to "come home now" – he began to panic.

He drove home to find his house packed up and Kate, Amelie and her parents all set to move to France. Simon now had nothing but the clothes on his back and no sooner had his family upped and left then Gemma appeared in the drive for her former husband to take out all his frustration on.

He shouted and screamed but she drove off, only for Tom to convince her to head back and offer Simon a hotel. Rather than thanking her, he stole her phone and marched off in search of his son, pursued by Gemma who swerved towards his miserable figure at the last minute.

Some key questions:

Who was Carly?

It's been two years since series one so you might not recall Carly, played by Claire-Hope Ashitey. She was a patient of Gemma's and was paid by the suspicious doctor to befriend young Kate and find out more about her. With her affair with Simon eventually exposed, it's no wonder Kate wasn't exactly pleased to see her old chum.

What did Simon tell Tom?

Simon continues to allude to what he told Gemma's son about her. He continues to claim Tom will never trust her like he once did, but viewers remain clueless as to exactly what information was passed on. And whether it's even true...

Did Gemma swerve to kill Simon?

The big question. After studying the end-footage several times, Gemma is most certainly driving towards the right of her husband when she swerves her car sharply to the left, presumably ploughing it into her ex-husband. With one more tense hour to come, we're not convinced she's finished him off for good. But did Gemma intent to hit Simon? Did she actually do so? They're all questions hanging over our heads for the next week...

This article was originally published in September 2017