According to an expert, nearly three decades after 23-year-old Amy Bradley went missing from a Caribbean cruise, a seemingly minor yet overlooked clue might unlock the mystery of her disappearance.

Amy disappeared during the early hours of March 21, 1998, while she was on a family vacation aboard the Rhapsody of the Seas, a Royal Caribbean cruise ship.

Even with a thorough investigation by the FBI and increased interest sparked by the Netflix docuseries titled ‘Amy Bradley Is Missing,’ her case remains one of the most perplexing unsolved mysteries of recent times.

But author James Renner, who has spent years researching her unexplained disappearance, believes there may be an overlooked explanation.

The True Crime Addict author even went as far as suggesting the three-part Netflix series, released on July 16, omitted important details about the missing woman.

‘In the facts of the case, there’s a small detail that doesn’t seem to mean anything – but it might mean everything,’ Renner told The US Sun.

‘They make a big point of saying that the balcony door was ajar in the morning, but they also suggest that Amy then left the room without telling anybody.’

Renner, who has interviewed cruise staff and studied internal briefings shared after the FBI investigation, pointed out the safety feature most cruise passengers may overlook.

‘If you’ve ever been on a cruise ship, you know that there are warning plaques in your room that say, “Do not open the cabin door when the balcony doors are open,”‘ he explained.

‘Because the hallway is pressurized. So, if you open that cabin door, it creates a wind tunnel. And it often causes the cabin door to slam shut – hard. 

‘You cannot quietly leave a cabin room with the balcony door open. It would’ve woken everybody up.’

Instead, Renner suggests, the answer lies outside, on the balcony itself.

While searching her seaside room, investigators discovered Amy’s palm prints on the balcony railing and her footprints on the glass door.

‘It appears she was sitting on the balcony with her feet against the glass,’ Renner suggested, adding, ‘it’s possible that she kicked off – and when she did, the door opened a little bit.’

He believes what happened may have been a tragic example of l’appel du vide – the French phrase for ‘the call of the void.’

‘She had a really rough night. She’d been drinking. And she had a very big decision to make when she got home: Does she live her life openly as a gay woman, or does she live a lie to maintain her close relationship with her family?’ Renner said.

Sitting alone on the balcony, Renner theorizes, Amy may have experienced a moment of emotional overwhelm and acted on impulse.

‘That voice inside you sometimes comes up and says, “What if?” I think she’s sitting on that balcony thinking, “What if?” And by pushing off, she causes action.’

Once overboard, Renner notes, survival is rare.

‘There’s only about a 20 percent chance you’re going to survive in the open sea long enough to be rescued,’ he said.

Renner’s theory stands in contrast to the widely circulated belief that Amy was abducted and sex-trafficked.

The unproven theory gained traction in the years following her disappearance, and has even drawn attention from aspiring lawyer and mega-celebrity Kim Kardashian.

Renner, however, dismisses the trafficking theory as improbable.

‘There is no verified account of a Caucasian woman being abducted and trafficked in the Caribbean,’ he said.

‘A white woman is going to stand out in Grenada. It’s not worth the risk for the people that do this. They have plenty of women from the Dominican Republic or Colombia who can go there and make more money than their family could in a year.’

Renner’s forthcoming book, A Cruise to Nowhere, explores the dynamic case.

‘For me, I’ve narrowed down what happened to Amy Bradley… I don’t believe she ever came off that balcony,’ he said.

‘I think it’s highly likely that she is responsible for whatever took place there.’

Amy’s body has never been recovered, and her official status remains missing.

The Bradley family has not publicly responded to Renner’s claims.

Daily Mail has reached out to Netflix for comment.