For a group of fundraisers are putting themselves in the position of the homeless people they are trying to help - by facing the elements and sleeping rough overnight on the rooftop of the Glasgow City Mission building.
The staff at Hymans Robertson could endure the worst of Scottish weather with wind and rain, and temperatures below zero predicted for Thursday evening when they will begin their challenge.
And the fundraisers will not be able to soften the blow with home comforts as they can only complete their task armed with just sleeping bags and cardboard boxes.
The group - Claire Campbell, Alan Purdie, Eddie McAuley, Iain Little, Marri Russell, Pat Kedslie, Peter Feerick and Kate Dix - will be the first ever to sleep rough on the top of the building to fundraise for Glasgow City Mission.
The idea came about after the firm's in house charity group Helping Hands thought of ways to fundraise for the charities they support throughout the year, and the Big Sleepout was suggested.
They hope to raise at least £5,000 for the Glasgow City Mission, which helps vulnerable and disadvantage people in the city through projects such as a hot food drop-in session.
Lawyer Claire Campbell, who is one of the fundraisers taking part, said: "I hope taking part in the challenge will help us understand the plight of the homeless. We only have to, however, do it for one night and experience the rain and cold. It will perhaps bring what they go through a lot closer to home for us.
"It is going to be a tough challenge, but this a great charity and we hope by doing this, we will raise more awareness of the wonderful work they do."
The group will even go straight back into work the following day which was a deliberate action taken by them.
Claire added: "We feel going into work the next day shows how difficult it would be for someone who is in that situation and is trying to get themselves out of it through work. If you have to go to work the day after sleeping rough, it is tough."
Graham Steven, marketing and fundraising manager for the charity, said: "We do not get Government funding for what we do. We rely on local people to support us and the fact this local business is willing to support us in this way is phenomenal."
You can support the cause by visiting http://www.justgiving.com/glasgowcitymission
For more information on the charity, visit http://www.glasgowcitymission.com/