After months in one of the world’s top hospitals, the family of Alyssa Gilderhus helped her escape.

In the ordeal captured on video, Alyssa’s stepfather helped her out of her wheelchair and into a car, her mother at the wheel ready to take off.

Mayo Clinic staff were running towards them. One grabbed Alyssa’s arm.

They then drove quickly away from the hospital that first saved Alyssa’s life, then allegedly held her captive.

The family toldCNN journalists Elizabeth Cohen and John Bonifield their story.

Christmas Day, 2016.

As CNNreports, the 18-year-old had just opened up her first Christmas present, a pair of cowboy boots, before going to the bathroom.

Her parents, mother Amber Engebretson and stepfather Duane Engebretson heard her scream. They found her curled up on the bathroom floor, vomiting. Her left side was weak and she couldn’t hear out of her left ear.

At a local hospital, doctors determined that she’d had a ruptured brain aneurysm. With her life on the line, doctors drilled a hole into her skull to relieve the pressure on her brain.

Later that day she was transferred to world-renowned medical centre the Mayo Clinic, located 135 kilometres away in Rochester, Minnesota.

Doctors there gave her a “grim” two per cent chance of survival, and after four brain surgeries over the next month, Alyssa beat the odds and was transferred from the neurology unit to Mayo’s rehabilitation centre.

Isolation in rehab.

It was there that tensions between Alyssa’s family and clinic staff began to flare.

On February 22, 2017, Alyssa’s mother Amber was kicked out of Mayo after a disagreement with medical staff. Amber toldCNNa doctor told her she was not allowed to participate in Alyssa’s care and was banned from stepping foot on Mayo property.

Despite repeated requests from both Alyssa and her mother to transfer her to a different hospital, Mayo refused to let her leave.

In a Facebook post, Amber wrote that her daughter was “basically a prisoner of Mayo”.

CNNreports that Alyssa was examined by a psychiatrist who found she “lacked the capacity to make her own medical decisions”.

On February 27, Mayo staffers found out that Alyssa had been recording a video for her mother and took away her phone, laptop and tablet. They then refused to let visitors bring similar devices into her room and stopped allowing visitors to stay overnight.

Alyssa Gilderhus says neurosurgeons at the Mayo Clinic saved her life. Why then did she escape months later, as part of an event security initially deemed “a patient abduction”? https://t.co/jxZlqutnFX pic.twitter.com/bREHDmVGmf

— CNN Newsroom (@CNNnewsroom) August 13, 2018

The escape plan.

“Alyssa, we’re going to go home honey,” she said to her daughter.

Two women in scrubs ran towards them as Duane bundled Alyssa into the car. As one grabbed Alyssa’s arm, Duane told her to get her hands off his daughter.

Once in the car, Duane yelled at his wife to drive: “Get out of here Amber. Go, go, go, go, go, go!”.

Alyssa's stepfather Duane Engebretson helped her into the car before they made their getaway. Image: CNN.

'Patient abduction'.

On the run.

The Sanford doctors disagreed with Mayo's findings, and ruled that Alyssa did in fact have the mental capacity to make her own medical decisions, and sign her own consent forms.

The family was free to go home.

A few months after she left Mayo Clinic, Alyssa, pictured with her mother Amber, was voted prom queen. Image: Facebook.

Mayo Clinic responds.

Mayo Clinic has disputedCNN's version of events.

To read the full two-part CNN investigation, by Elizabeth Cohen and John Bonifield, click here .