EastEnders will air a huge disaster in Walford next week when a devastating car crash changes lives forever.

The awful accident occurs in the wake of huge secrets being exposed that threaten to tear the Mitchell family apart, with other unsuspecting locals getting caught in the crossfire.

The drama begins with Zack Hudson secretly plotting to flee Walford, taking Barney Mitchell with him. Following recent revelations about Shireen Bashar, Zack fears his biological son isn’t safe around his mum and is putting plans in place to get him away.

Needing some cash, Zack asks Ravi Gulati for a loan. Upon hearing what Zack has up his sleeve, Ravi warns him about Nicola Mitchell, revealing she recently asked him to move a dead body.

This makes Zack even more convinced Nicola is trouble and he must cut her out of Barney’s life, but the teen still has no clue about his true paternity.

“Zack has a heart-to-heart with Linda and tells her what he’s learnt about Nicola,” reveals our source. “Linda urges Zack to go to the police to protect Barney. It’s a risk, but Zack feels he has no choice – and as a result, Nicola is arrested.”

The Mitchells reel as Nicola is taken in for questioning, and when Zack clocks Harry Mitchell’s reaction to his mother’s arrest, he wonders if Barney’s brother could become an unlikely ally.

Zack informs Harry who Barney’s biological father is, hoping the mechanic hates his murderous mum enough to turn against her and help get his sibling to safety.

“Nicola is eventually released pending further enquiries, and she’s soon back on the Square,” shares our insider. “But Harry storms in and announces the secret Nicola has spent 16 years trying to hide – Teddy isn’t Barney’s biological dad, Zack is.”

While Nicola desperately denies Harry’s claims, Teddy can see right through her, and she has no choice but to admit everything.

As Nicola tries to explain herself in an emotional showdown, Harry realises where his loyalties lie and reveals Zack is planning to run away with Barney.

“Nicola and Teddy try to stop Zack,” explains our source, “but Harry is one step ahead and sneaks off to derail his plans. He confronts Zack, bundles him into the boot of his car and drives off. Teddy soon works out what Harry has done and decides to intervene before things get out of hand.”

Teddy gets a lift from Billy and Honey Mitchell and Nigel Bates, hoping to catch up with Harry. After a dramatic chase, it looks as though Teddy has everything under control – until things take an unexpected turn.

One of the cars suddenly swerves and ends up veering off the road into a lake. As some of the passengers scramble out of the vehicle, they try to save those trapped before they sink into the water.

But which car has taken a plunge, and who will make it out alive?