All of his friends cancelled on his fourth birthday party so 55 strangers saved the day.

What do you do when all the guests for your son’s fourth birthday party abandon you at the last minute?

You turn to your Facebook mothers group.

And a little boy’s day becomes magic.

Rachelle Briannan and her two children. Via Facebook.

The story of how a Melbourne Facebook group of mums saved a little boy's birthday is touching hearts right around the world after a post from the page went viral.

On Sunday a teary mother took to her Facebook mother's group - a page called Midnight Mums.

She was horrified - it was her son's fourth birthday and  all of his friends had either cancelled or not bothered to reply to her party invitation.

Mum of two Rachelle Briannan wrote: "So I'm sitting in my room quietly crying. 12 kids were invited to my sons party today, and an hour before every one of them cancels or just doesn't reply to my msgs [sic].

"My son just turned 4 and this is the first time he's really understood the whole party with friends thing. My heart is literally broken for him!! I'm so hurt and angry [sic].

"What the hell can I do to make this up to him? Seriously. Like I made him this huge superhero cake and there's going to be no one to even sing happy birthday to him."

But within minutes, 25 mums and dads from across Melbourne harnessed their parent power and showed just how social media can be used for good.

To her amazement within the hour 55 people - including 30 children had gathered at aMcDonald's restaurant, in Eltham, in Melbourne’s north-east to help the little boy celebrate his birthday.

But there was more the group had also prepared a special surprise for Taenon, not only had they managed to bring a large bunch of Number four shaped balloons from party supplier Veronica’s Party, they had also asked volunteers from Nillumbuk SES to attend so the children could explore the trucks.

Midnight Mums proudly posted on Facebook about the astonishing achievement writing: "The Midnight Mums community rallied together online with hundreds of birthday wishes for Taenon flooding our newsfeeds and touching the hearts of our members with this feel good story right across Australia and beyond".

The kids even got to explore the SES trucks. Via Midnight Mums.

Blogger Constance Hall who got wind of the event wrote on her Facebook page that things like this happened.

"This happens, we have all had to pull out of a kids party on the odd occasion, we just have to hope that we aren’t all pulling out of the same one," she wrote.

"So Taenon’s mum Rachelle Briannan of Melbourne did what most modern mums in the year 2016 would do and she vented publicly in a post to a big Facebook online mothers group about the heart ache that comes with organising a huge party for your little man and knowing that his heart was about to break."

"Rachelle was and still is speechless,"

"Taenon was over the moon, had the best day. Queens smashed this party out and what on earth is more important then a little sweet pea on his fourth birthday"

Happy Birthday Taenon and Midnight Mums - you guys are the best.