Police described the community response as “overwhelming”, with many searching through the night without a break.
Shortly before 10am, about 500 gathered at a community centre in Muirhouse to await police instructions. They gave their names and e-mail addresses and were sent to Cramond.
At midday, a human chain of firefighters and volunteers was formed, stretching up from the promenade to the road. Volunteers walked slowly and silently eastwards, eyes fixed firmly on the muddy grass below.
All the time, two helicopters hovered in the slate grey sky, the low buzzing sound providing a backdrop to police instructions and quiet chatter.
When the line reached woodland, it broke up slightly. Several former bonfires were picked apart as branches, car tyres and wheelbarrows were overturned in the hope of finding anything linked to three-year-old Mikaeel.
Councillors Vicki Redpath and Cammy Day were both out for a second day.
Mr Day said: “I left at 3am and came back at 9am, and there were people out even before that.”
Ms Redpath said: “This is evidence of the character of the people of north Edinburgh. There’s this hope and belief that it could yet still have a happy ending. We’ve got to keep that thought in our heads and our hearts.”
Police are looking into the possibility that a crime has been committed, having put together a timeline of Mikaeel’s movements leading up to Wednesday night, and are broadening their investigations.
But for the volunteers, the only consideration was that a little boy could be out in the Edinburgh cold.
Last week, hardly any of them had ever met Mikaeel Kular. Now their only concern was his safe return.
Shona Clemson, 41, said: “I saw it on Twitter and asked a friend if she wanted to come along.
“We are both mums, so you can empathise with his mum and how she must be feeling, thinking of him hiding out there somewhere on his own.
“It is really concerning. He is so small that he would not know how to look after himself or where to go for safety.”
Sharon Aitchison, 42, said: “I live out in Newbridge, I’m a foster carer and work with children. I’m just going to follow the professionals and do what they want us to do, and hope that someone finds him sooner or later.”
The Kular family are constituents of Colin Keir MSP, who said criminal investigations and hypotheses were for others – their concern was for a little boy.
“It’s extremely concerning,” he said. “A three-year-old is a different proposition, even to a five- or six-year-old, who is that bit more experienced.
“I hope he is holed up somewhere dry and warm, whether it’s a property or a rabbit hutch or hut. Maybe he is scared to come home and feels he has done something wrong.
“I don’t think people should be speculating about what’s happened. The big priority is let’s get this wee laddie home as soon as possible. Those answers will follow once we’ve got him home and safe.”
After searching woodland, the line reformed and passed more grassland. Their cold, grim march conveyed little hope of a happy ending.
They reached further woodland and this time the group separated for good.
Firefighters, with sturdy footwear and suits, took the rougher terrain. Underfoot were rocks and leaves, mud and streams, the occasional plastic bag or strewn rubbish.
David Farries led a team of 16 redeployed Edinburgh firefighters, adding their expertise to the efforts of volunteers.
He said: “We are an integral part of this community – cover has been provided for emergencies elsewhere in the city, so there’s nothing else to do but to come and assist. It’s fantastic to see such support.”
One woman found a child’s glove, although seemingly for someone older than Mikaeel, another found brown shoes, potentially similar to the ones the three-year-old was said to be wearing.
But none of these finds triggered a fresh line of inquiry.
The search passed Muirhouse mansion and petered out as it reached Edinburgh College, leaving a few people disappointed.
Jim Elliott, 67, from Craigleith, questioned the level of organisation from the police.
“We were not asked to do anything. It was a bit shambolic,” he said. “We joined the line but no-one said what we were looking for. We had to organise ourselves.
“There’s so much rubbish, it’s hard to know what is relevant. No-one has been telling us anything, but we do appreciate that it is difficult.”
Inspector David Happs, who briefed the volunteers in the morning, urged people not to take young children.
“Health and safety is important,” he told the gathered crowd. “It’s dry and relatively warm now, but there are wellies available. I can see some young children, and this may not be suitable for some of them. I know you are enthusiastic and keen to help, but balance that with your own health and safety.”
Many had braved harsher elements the night before.
Sarah Wakeley, 33, said: “There was a group of us out last night checking bushes and open areas, going down the beach and round the housing estate, shouting out his name.
“I was out from 12 to 12. It’s my wee boy’s seventh birthday today. If it was my kid, I would hope people would do this.”
While everyone remained hopeful, there was no denying how tough it was to be out after dark, even for adults. “It was freezing, proper freezing,” Ms Wakeley said.
Angela McNeill, 39, and Amber Stromach, 26, did not know each other previously, but spent the whole night searching together, bouncing off one another and fighting through the exhaustion and the rain.
Ms McNeill said: “We’ve been searching around the railways – we went round past the golf course at about 12 last night.
“We’re tired and we were soaked through to our skins. I could not feel my fingers it was so cold, but we never thought about going home.”
Asda, Morrisons, Halls and Stoats porridge all donated food and drink, while several companies let people take the day off to join the search.
All those who spent countless hours in the cold and rain will hope their efforts do not prove to have been in vain.