Insomnia ending explained: How does Vicky McClure's thriller end?

She’s been arrested for her mother’s murder, lost her job at a high-flying family law firm, her teenage daughter Chloe (India Fowler) has been outed for having an affair with their married family friend, and she nearly ran someone over.

To top it off, she’s sleepwalking in the night and almost smothered her son, Will.

That’s enough for anyone to lose sleep over, but it comes at a far higher cost for Emma, who is haunted by a series of numbers and has been leaving her husband, Robert (Tom Cullen), and kids terrified by actions in the night she has no recollection of.

Despite seeming efforts to look after her by Robert, sister Phoebe (Leanne Best) and new friend Caroline (Lyndsey Marshal), Emma is convinced her worst fears are coming true, and she’s destined to go insane at the age of 40, just like her mother did.

But things aren’t always as they seem, and as she digs into her past to try and find answers, it becomes clear that an outside force is trying to stop her getting too close to the truth.

The key seems to lie in the foster home she stayed in as a child, and where she almost drowned after being pushed into a lake by someone.

Caroline is not who she appears to be, either, and in episode 5 the wheels fully come off as she runs Phoebe over, kills her mother and then bakes Emma a birthday cake laced with amphetamines.

As she arrives at Emma’s house and is welcomed into the home by an unsuspecting Robert, here’s what happened as the truth finally came out.

Insomnia ending explained

Who is Caroline?

As Caroline walks into Emma and Robert’s home, her plan soon fully comes to light. She doesn’t want to be Emma’s friend - she wants to be Emma.

Caroline is the daughter of a couple who, at one point in time, wanted to adopt Emma, and had even gone to meet her at the children's home in preparation.

Young Caroline believed this meant she wasn’t enough for her parents, and en route home threw an almighty strop, causing her parents to lose control of the car and crash.

While Caroline left the accident unscathed, her parents were badly injured, and because she didn’t like the sound of her dad’s painful choking sounds, she smothered him at the scene to make him stop.

Her mother survived the accident but was left paralysed, and Caroline became her carer. Caroline has blamed Emma ever since for taking away her family unit, and was furious that she had the "perfect" life she believed she deserved.

So, when Emma’s mother came into the hospital where she worked, she seized the opportunity to get her revenge.

Smothering Emma’s mother and then befriending Emma, she infiltrated her life, and now wants it for herself as she believed she deserved it.

Drugging an unsuspecting Robert and Chloe with the cake she brought to their home, Caroline proceeded to drink her wine, wear her lingerie, and dance around the house waiting for Emma to return.

Julian (Dominic Tighe), the man teen Chloe had an affair with, makes an unexpected arrival to the house when Chloe, who is now passed out from the drugs, doesn’t return his calls.

As he suspects something is wrong, he tries to gain entry into the house, but Caroline kills him with a wine glass, dragging his body into the lake to hide what she’s done.

As Emma finally arrives, she tries to reason with Caroline, even trying to act like she’s her friend to get her to calm down, but it does no good.

In the tussle that follows, Caroline stabs Emma in the stomach, leaving her collapsed on the floor.

Young Will, who was asleep upstairs when Caroline first drugged the family, is caught hiding in a closet, and when he’s found Caroline puts him to bed and attempts to smother him.

Thankfully, Emma hits Caroline over the head and saves her son, just as the police arrive.

What did the numbers mean?

In the aftermath of the horrors, Emma and Robert decide it’s best to have a fresh start and sell up their home.

As they begin to pack, Emma and Phoebe discuss what went down over a cup of tea, and Emma discloses that she’s discovered what the numbers mean.

She tells her sister that the "curse" put upon her is actually the gift of foresight – albeit a very convoluted, hard-to-decipher foresight.

Acting as a warning for Caroline’s attack, the numbers were actually timestamps for when key events from the night occurred.

Her sleepwalking was actually a recreation of events before they even happened, with Emma taking on the role of Caroline. She realised the numbers’ significance while looking through security cam footage.

While she cannot explain how or why she was given this warning, Emma says she’s satisfied the entire situation has ended, and with Phoebe, she toasts to a new life as a family.

However, as the episode comes to a close, Will is seen upstairs in his bedroom, chillingly writing a new series of numbers on the wall.

Insomnia is available exclusively on Paramount Plus in the UK now – get a seven-day free trial on Amazon Prime Video.

Check out more of our Drama coverage or visit our TV Guide and Streaming Guide to find out what's on. For more from the biggest stars in TV, listen to The Radio Times Podcast.