Drugs mule Melissa Reid was caught smuggling £1.5 million of cocaine out of Peru so she could "boast about it" to friends in Ibiza.
The 22-year-old spent three years in a Peruvian jail alongside 23-year-old Michaella McCollum after they were caught trying to take 24lb of the drug out of the country.
The pair - nicknamed the "Peru Two" - were jailed for six years and eight months after admitting the offence.
Reid has now returned to the UK, having been released from jail in Peru earlier this month.
McCollum was freed in March under new legislation but was required to remain on parole in Peru.
Speaking to the Scottish Mail on Sunday, Reid explained how in summer 2013, aged 19, she had flown to Ibiza with a friend to spend the season on the Spanish island.
But the holiday turned into a spiral of taking hard drugs and clubbing that led her to a British woman acting as a recruitment agent for drug smuggling gangsters.
Reid was then offered £4,100 to fly to Argentina and return a matter of days later with a package in her luggage.
I thought it sounded like a challenge and was blase about it.
Reid said that she "wasn't in the right state of mind" and living a "ridiculous life".
"[I] wanted to show I could manage it. I now realise that I put myself at risk and no one would have known where I was if anything had happened to me, but I didn't care at the time", she said.
Reid flew first to Majorca where she met McCollum for the first time.
After two nights in a house with a group of armed gangsters she moved on to Madrid, where she was told she would be going to Peru instead.
"I just went along with it. The guys had guns but I was never threatened," she said.
Reid was arrested as she tried to pass security at Lima airport on her return with the cocaine packed in her suitcase.
Her mother, Debbie Reid, described the moment she found out in a telephone call: "[They said] 'Mrs Reid? It's the Foreign Office here. Are you sitting down? I'm afraid your daughter has been arrested in Peru for drug-smuggling."
In an attempt to reduce her culpability Reid followed instructions the gang had given her before her departure - that she had been forced to smuggle the drugs against her will.
"We thought we would be believed and it would all go away, but we were wrong," she said.