Their ordeal began after dinner just off the neon bustle of Bangla Rd, a 400-metre strip of bars, clubs and hawkers.
With sightseeing planned the next day, they went for one drink in a pub before an early night. It was about 9pm.
After they ordered, a Russian couple approached. She was mid-30s, attractive with short blonde hair and blue eyes. He was big, like he worked out, early 40s. The Russians seemed friendly, they invited them to join them.
Sally and her fiancé's sister went to dance. The blonde followed. She bought them a drink. Things started going hazy.
"The Russian girl kept on touching my face, my hair, staying 'you're beautiful'," said Sally. "I started feeling a bit awkward, but a bit strange as well.
"Then she said, the boys are going to the pub across the road, let's go to see them'. I didn't think to look around. We followed her and she introduced us to these guys. My fiancé's sister seems to remember they were Albanian.
"They had drinks — I'm not sure if I drank that drink. I know [the sister] did because she said it was a mojito. From then, nothing, I can't remember anything."
She's pieced together the rest of the night from what her fiancé and cousin told her.
"Back at the first pub, the Russian lady joined the table again. The Russian man kept on talking about how he used to work in the military.
"He kept asking my fiancé whether he trained, could he fight, like he was sizing him up. The guy would come up and say 'try and get out of this' and put him in a lock."
Rattled, her fiancé decided to go, the Russians asking what he was doing.
"He said he was looking for the girls. They were saying 'they're fine'. The more they said that, the more my fiancé got upset. He usually knows where I am and his sister was 23, 24 at the time.
"Our cellphones weren't working — they weren't on roaming. The Russians kept following. He told them to back off and they said 'they're fine'. He turned round and said, 'they're not, they're gone'.
"That's when the guy said, 'well in that case if you ever want to see them again you have to come with us'. And that's when my fiancé got absolute chills."
Shaking off the Russians he ran to check the hotel. Their rooms were empty.
"He was frantic. He was crying, screaming, waking up all the guests, the hotel staff came out. He said, 'my sister and fiancé are missing — we need help'."
Sally's cousin flagged a tuk tuk. Spooked, the driver refused to take them all the way to their hotel. Another dropped them on the lawn outside.
"My fiancé thought I was dead," said Sally. "Apparently my eyeballs were completely rolled back. He just broke down and said, 'why did you bring me a dead fiancé?'."
The women were taken to hospital.
"I woke up the following evening at the hotel," said Sally. "My hair was dirty, my clothes were dirty, I was full of bruises, I could see where the drip had been. I was, 'where am I, what's going on?'"
There were no blood tests. The nurses were helpful but treated them like "foreigners on a bender". Some six hours after entering the first pub, they were discharged.
"It wasn't a drunk night at all," said Sally. "I knew exactly how much I had drunk."
"For a couple of days after I couldn't do any sort of maths, I couldn't speak properly, I wasn't making sense at all. It took a couple of weeks to recover from all of it. I still have absolutely no memory. But I'll never forget that Russian lady's face — ever."
Shellshocked, the group spent the rest of the holiday at the hotel. They found news stories about local women spiking male tourists, but nothing like their experience.
Sally's speaking out now to warn other holidaymakers: "Keep your guard up. You think this kind of thing is going to happen to a 20-year-old on holiday with friends getting drunk all night but this can be a family thing."
Thailand is increasingly popular with New Zealand residents, more than 51,000 listing it as their main destination in the year to June 30.
The Government's SafeTravel website notes drink-spiking at various holiday locations in Thailand, with male and female victims.
Sally believes she could have been the victim of attempted human trafficking. Her fiancé still freaks out if she goes missing for an hour and she's warier than she was, particularly when walking home alone in the dark.
"I've been reading these books about trafficking recently and how it's so easy and I always think, God, anyone could just pull up now and no one would know. It's still very unreal."
How to avoid drink spiking in Patong
• Always buy your own drink — bottles, not open drinks like cocktails.
• Watch your drink when interacting with groups.
• Finish your drink before going to the toilet.
• If you feel drowsier than usual, leave and get help. Call the Patong Tourist Police on 1155.