On a hot and windy September day in Sydney's west, two young Aussies met up with their mates to have the time of their lives.

They had never met each other but, later that day, they would both die in the same hospital, in excruciating pain and within just 35 minutes of each other.

An inquest this week heard how Diana Nguyen, 21, and Joseph Pham, 23, were essentially internally cooked to death after taking MDMA — sending their bodies temperatures into an uncontrollable overdrive, news.com.au reports.

The pair had arrived at the event separately at the Sydney International Regatta Centre in Castlereagh on September 15 for the event, which was billed as one of the biggest and most exciting "hardstyle" dance music events in the world.

Melbourne airport worker Ms Nguyen, who had "loads of friends and loved going to school" where she met her fiance when she was 14, arrived at the festival that day.

Like the rest of the 30,000 patrons at the sold-out event, she loved the thumping sound of hardstyle dance music, but aside from that she had studied courses in fashion and beauty and loved playing soccer.

"Those who knew her described her as a happy and energetic person who loved going out," counsel assisting the coroner, Dr Peggy Dwyer told this week's inquest into six drug-related deaths at NSW music festivals.

CCTV shows Mr Pham being take out of Defqon. 1. Photo / 10 News

"But, she wasn't known for taking a lot of drugs."

The court heard she'd taken caps "sporadically" in recent years, but it's likely hadn't done so for up a year before that fateful September day.

This is evidenced in haunting texts tendered as evidence to the inquest.

They show how Ms Nguyen' fiance urged her to not to take "too much" MDMA in texts sent between September 14-15.

"Stay safe please n dont take too much please," he wrote.

"I Think im going to take 1 (MDMA cap) hahah," Ms Nguyen wrote to her partner. "It's been so long I'm so scared."

"Okay babe jst stay safe n dont lose anything and also stay next too ur friends," her fiance wrote on the day of the festival, in the final message tendered as evidence between the couple.

It was on that day, at 1.30pm, Mr Pham — who the court heard was "community minded and full of promise" — was making his way to the festival with his brother.

The aspiring teacher was an ambassador for Defqon, who loved gaming, dance music and Japanese culture.

On the way to the event in a car with his brother, he picked up one of his school mates at Cabramatta train station, in Sydney's south west.

This friend, who can't be identified for legal reasons, told the inquest this week Mr Pham told him he "had some in his bag" shortly after picking him up.

He told the court he thought the purple-coloured pills in the black bumbag would have been MDMA because "when you go to those sorts of events that's what everyone takes".

"I don't like talking about drugs so I let him do what he wants to do," the man said. "That event is, like, known for drugs and his facial expression gave it away."

Mr Pham seemed excited, telling everyone in the car he was "pumped and ready to have a good time". His mate told the court he saw "four to five pills" in the bumbag.

There were dozens of police officers standing outside the entrance, and the friend told the court he was worried about Mr Pham being caught.

However, Mr Pham passed through without alerting the drug dogs, and the friend told court he initially took half a purple pill with water shortly after.

It was around that time, at 2pm, Ms Nguyen texted a mate asking who she could buy MDMA from and an hour later she and two friends entered through the festival gates, past a barricade of police officers with sniffer dogs.

They all had VIP passes, so their first port of call was the VIP tent — where Ms Nguyen drank three vodka and cranberry juices.

The court heard she arranged to buy three caps from someone she knew and the group bought an additional three from men they didn't know at the event.

They took one each and danced for an hour, but they soon began to sweat heavily on the scorching September day, so they made a make a beeline back to the VIP tent to hydrate at about 4.30pm.

An hour later, Ms Nguyen told her mates she "felt good", one mate said the pill was "wearing off" and the other said she was "wasted".

The pair that said they were feeling OK, decided they would both take another cap from the batch Ms Nguyen had bought separately.

At 6pm, the court heard Ms Nguyen was drinking water on the dance floor but appeared "shaky on her feet" — her friends said she was "hot to the touch and was incoherent and sweating".

It was an hour after that and not too far away from the girls that Mr Pham split up with the mate he'd picked up at Cabramatta, to join two other friends.

In a statement tendered as evidence in court, the friend said Mr Pham's mood when he lost sight of him was "energetic" and "happy".

However, he told the court he was shocked when Mr Pham told him he'd taken "three or four pills" throughout the day. He said Mr Pham was sweating, but not in an "unusual" way as he walked off to meet his other mates.

It was the last time he saw him alive.

Just 30 minutes later, at about 7.34pm, Mr Pham arrived at the festival's only medical tent, where Dr Andrew Beshara already had his hands full managing two "significant patients" including a psychosis post-MDMA ingestion and an asthma attack.

Dr Beshara said Mr Pham appeared "extremely unwell".

He was the junior of just two doctors in the tent and he told the court the medical team was "extremely busy" on the hot and dusty September day — constantly dealing with cases of asthma attacks and dehydration.

He said that when Mr Pham arrived he was "non-responsive" and the medical team searched him to find out what he had taken, but they had no luck.

Dr Beshara told the court he suggested an ambulance be called almost straight away, but between 10-15 minutes later Ms Nguyen was brought in after she had collapsed.

The court heard she was unconscious, twitching and spasming — which made it difficult for the medical team to open her mouth and give her oxygen.

Ice packs were used to cool her down, as her internal body temperature had soared to 39C — two degrees above normal.

Meanwhile, Dr Beshara was tending to Mr Pham, who was unresponsive with dilated pupils, his body temperature was also skyrocketing.

He was also experiencing "trismus" — spasming of the jaw muscles — as a result of his MDMA ingestion.

"His jaw was essentially wired shut, his arms and legs were tensed up and he was very stiff," Dr Beshara told the court. "Essentially from the moment we received him, he would need to be transferred."

But an ambulance wasn't ready to take him to Nepean Hospital until around 8.35pm and it wasn't until 9.05pm that Ms Nguyen was taken to the same facility.

Despite the frantic efforts of the doctors and medical staff in the emergency department Mr Pham was pronounced dead at 9.42pm and Ms Nguyen died at 10.17pm.

Autopsies found they both died of MDMA toxicity and Dr Dwyer told the court both had extremely high body temperatures before their deaths.

"Once body temperatures rise above 40 degrees celsius the body's ability to regulate its own temperature becomes severely impaired," Dr Dwyer told the court.

"At this point, temperatures continue to rise, leading potentially to multi-organ failure, impaired blood clotting and ultimately cerebral oedema. Mortality from drug induced hyperthermia with temperatures above 40 degrees celsius is high."

The evidence surrounding the tragic events was given as part of a two-week inquest looking at the drug-related deaths of six young people at NSW music festivals between December 2017 and January 2019.

Deputy State Coroner Harriet Grahame is examining Ms Nguyen and Mr Pham's deaths alongside those of Callum Brosnan, Joshua Tam and Alexandra Ross-King — all aged between 18 and 23 — who also died from MDMA toxicity or complications of MDMA use.