When I was in college,5 of us decided that we were going to attempt to climb Laramie Peak. It's not a huge peak, but it is very prominent and very easy to see for a really long way.
Some of the others had a school function and so we did not get started driving until around midnight. It was probably an hour and a half drive, and it turned out that the directions I had did not account for a road being closed. Eventually, we gave up trying to find it in the dark and slept in the vehicle.
When we woke up, we had an awesome view of the peak which had a large lenticular cloud streaming past the summit. We decided to attempt to climb it from the east side, starting out at a Boy Scout camp and then just heading up (the trail was on the other side of the mountain).
First, we had a small mountain to climb with a fire watching tower on top, where we stopped and had lunch. Then we went back down that mountain, finding a large bull snake about halfway down, before finally heading up Laramie Peak. We stuck to the top of the easternmost ridge, weaving our way up around various dead logs and rock outcroppings.
Finally, we decide that if we were not at the top by 5:30 pm we would have to turn around regardless. When 5:30 pm came, we were within a half a mile and 1,000 vertical feet of the top, but it was starting to snow and we headed back down the mountain.
About half a mile from the saddle between Laramie Peak and the little mountain, I turned around and looked back up and there was a blanket of fog heading down the mountain towards us. Very shortly there was a blanket of fog coming down the small mountain ahead of us as well. We reached the saddle just as it got dark, and the fog reached us about the same time.
The rest of the night was a blur of hiking in the dark, dehydrated, out of food and crossing rock slabs of uncertain height.
We eventually made it all the way back to the vehicle and from there back to school. It was one heck of an epic adventure.