After days of focusing on urban parkland in the search for missing Karen Buckley, suddenly there was a major shift in the case last night.
And a new scene became the focus of intensive police activity, at a farm and golf course north of Glasgow.
Officers cordoned off High Craigton Farm, in Milngavie, just outside Glasgow. Several police vehicles, including an environmental protection unit which deals with incidents involving breathing apparatus, were seen driving on to the site.
There was also police activity at the nearby Windyhill Golf Club. The heavy whirr of helicopter blades filled the air above a large, thickly wooded area at the top of a hill behind the farmland.
A mobile incident room was also driven into the area, with a massive police presence along the narrow roads and scores of officers moving on site.
Investigators had issued an appeal for information on Monday after a grey car was spotted on the twisting country roads nearby. They received a number of calls about the car from concerned members of the public.
As the search intensified, it emerged that a man had been detained by police investigating the disappearance of the Co Cork-born student.
As the news of the latest developments spread through the city and beyond on social media, concern for Karen continued to mount.
Glasgow is known for being rough and ready, a vibrant and friendly city despite a reputation for problems with drugs and deprivation. But yesterday the whole city was numb with shock.
Locals muttered "this just doesn't happen here" - with many expressing concern for their own young families.
Taxi driver Kevin Butler said the ordeal, which dominated national and local titles in Scotland again yesterday, left him worried. "I have a young daughter, the thoughts of letting her out is absolutely terrifying," he said.
"I always considered Glasgow a very safe city, I have spent my whole life here. I know it has its problems ... but this has me worried."
Talk in the city's pubs and cafés was also focused on the fate of the missing 24-year-old. Her friends set up an internet fundraiser to help cover the family's expenses, with donations pouring in. .
"This is priority number one at the moment for Scotland," said Detective Superintendent Jim Kerr.
Hundreds of Scottish police officers took to the search effort, with many giving up their time voluntarily.
Ground units were joined by specialist officers who spent the day combing Dawsholm Park and the surrounding area.
A constant hum of the police helicopter was ever present in the blustery city as the air unit offered support to those below.
Marine units continued to search the icy waters of the Kelvin River while specialist crime division teams and police dogs scoured the ground.
The dozens of highly-trained police searchers had set out yesterday with the heartbreaking words of a mother echoing in their ears.
"We just want Karen home safely, we are desperate. She is our only daughter, we love her dearly," said Marian Buckley (61), as she stepped out into the glare of the cameras in a bid to jog people's memories.
As the hours ticked by Marian and John Buckley, whisked from their quiet life in rural Mourneabbey and dropped into a nightmare, were kept informed of developments.
Forensic officers carrying boxes and black bags were seen leaving the property in Dorchester Avenue, where Karen was believed to have gone with 21-year-old Alexander Pacteau before she disappeared. He was spotted on CCTV talking to Karen outside Sanctuary nightclub, where she was last seen by friends. Previously, police had said he was not a suspect - but he admitted taking Karen back to his flat in the early hours of Sunday, claiming she left at 4am.
Another major breakthrough had come when a member of the public found Ms Buckley's handbag in a bin in Dawsholm Park on Monday.
Night fell on the Scottish city, but the police search continued apace. Yet hopes of a positive outcome seemed to be fading with the daylight.