The Cuckoo ending explained: What happened to Sian?

Throughout the new Channel 5 series, we followed Sian (Jill Halfpenny) as she moved in as a lodger in Jessica (Claire Goose) and Nick's (Lee Ingleby) home. But there, she soon started to form a bond with their teenage daughter Alice (Freya Hannan-Mills), growing close over art and their shared feelings of being outsiders. Eventually, Sian revealed that she's actually Alice's biological mother.

As part of a ploy to win back her daughter, Sian moved in with the family but with Alice having never even known she was adopted by Nick and Jessica, it's a lot to wrap her head around. The final fourth episode followed on from Sian attacking Jessica and locking her in a cupboard, running away with Alice in the process.

But how did things unfold in the finale? Read on for a full breakdown of the ending of The Cuckoo on Channel 5.

The Cuckoo ending explained: What happened to Sian?

The final episode starts with Jessica trying to get out of the cupboard that Sian locked her in in the previous episode. When finally released from the police station in the morning, Nick goes home to find a frantic Jessica who has managed to escape. But before they can even have a debrief about what happened with the police, Jessica tells him that Sian has taken Alice and they have to go and find her.

On the road, Sian is starting to feel uneasy about what they've done and floats the idea of returning to Jessica to check she's alright. Feeling sick, they stop at a petrol station where Alice manages to leave to go to the toilet to listen to the voicemail from her mother. But Sian finds her and convinces her that Jessica and Nick don't care about her. At the same time, Nick and Jessica are using the tracker on Alice's phone to locate her but when they finally reach the petrol station, they find Alice's phone and see that she was about to send a message to Jessica.

They inform the police and eventually look back over Sian's reference that she provided when she moved in, which gives them the address of her aunt Fay. They visit Fay and there they learn the truth about Sian's past and that Sian thinks Alice is her biological daughter.

Meanwhile, Sian has taken Alice to a desolate caravan park where she has fond memories. It's the same caravan park that is in a picture of a teenage Sian which Fay shows Jessica and Nick, who ask her to tell them exactly where it is.

Arriving at the park, the pair have no phone connection but agree to go in separate directions to find Alice. Alice is getting more upset as Sian describes her daughter, with Alice clearly no longer believing it's true and feeling scared. Alice hits Sian over the head and begs her for the keys to let her out, screaming as she leaves and alerting her parents to her whereabouts in the process.

But as Sian gets back up, she retrieves a knife from the kitchen and goes looking for her. Nick starts calling out for Alice but Sian uses that as an opportunity to locate where he is and when she finds him in her caravan, she stabs him. Nick is left on the floor and Jessica approaches the caravan, seeing Sian holding a bloody knife. Sian runs off after hearing Alice calling out for her mother and tailing after her, Jessica stops to see if Nick is alright but he quickly dismisses her and tells her to find Alice.

Alice is on the edge of a cliff overlooking the sea and is pulled back by Sian, who is confused when Jessica runs down to tell her that Alice isn't Sian's daughter. Jessica tries reaching for the knife on the floor but Sian jumps on her and the pair get into a fight. In order to break it up, Alice lies and says that she remembers that Sian is her mother.

Sian is happy and relieved but takes steps back towards the edge of the cliff, saying this is what birds do: "They fly away and they come back." She admits she just wants to be with her baby and those are her final words before she falls back into the crashing waves below.

Was Sian actually Alice's biological mother?

Aunt Fay tells Nick and Jessica that there was a couple from the church who wanted to take Sian's baby once she was born but she said that Sian wouldn't listen. Sadly, Sian's baby died on the morning she was born – 7th September, which also happens to be Alice's birthday.

Aunt Fay explains that Sian found a "crook" to find the adopted babies with the same birthday and name, which is why Sian thinks that Alice is her daughter. But Fay admits that Sian has never faced up to the reality of her baby being dead.

When Sian details her birthing story to Alice, she grows disconnected and tells Alice that she ran away because those around her wanted to take her baby away from her and she came to the caravan park to give birth, not wanting to go to a hospital for fear of losing custody.

Sian later says in her tearful confession to Alice on the cliff that she "held her too close" when she was a baby, which could point at the cause of death.

What happened to Nick, Jessica and Alice?

After Sian falls from the cliff, we then fast forward to Nick and Jessica's home where the police officer is telling them that they can't officially declare that Sian is dead as no body has been recovered. So, Nick survived being stabbed by Sian.

With their furniture packed up and moving people sorting their stuff out, the pair don't say they're moving back to London but are considering their options. Everything seems alright with the family as Jessica helps Alice pack away her drawings.

Did Sian die at the end of The Cuckoo?

Although we see Sian fall, no body is ever recovered. The final shot of the series is of an impressive looking home that bears a resemblance to Nick and Jessica's former country house. We see someone use the knocker on the door and a teenage girl answers the door to see a woman turn around. Although the image is purposely blurry, it's clear it's Sian.

Sian is not actually dead so could she be looking to strike again? From what her aunt Fay has said, it's a pattern of behaviour that Sian seems to be continuing.

The Cuckoo is available to stream on My5.

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