Mike and Phil are putting up a lot of Christmas lights and they blow a fuse. Doctor Cecilia shows them an invention that she is working on and when Mike opens a window, the plans fly out and he and Phil must track it down and get the plans back. This reminds Phil of a time when Cro invented something.
We flashback to many years ago and Cro and Pakka are enjoying skiing down the snow covered slope much to the disgust of Earl and Mojo. Earl is trying to get all the mammoths to gather firewood for their annual wintertime hot tub soak. Phil and Ivana go up and check her device that measures wind speed and they find that the winds is constant in the area on the mountain where she placed the device.
Cro shows Ogg, Gogg, Mandy, and Bobb how to ski and they really enjoy it. The next day they try and go up the mountain, but the sun has melted the snow and now it is ice. Cro has an idea and he creates a pulley system that can pull the Neanderthals up the mountain one at a time. This is great for them but when Ivana tries it, they find out that they need more power to get her up. Phil creates a leaver on one end of the pulley and he is able to lift her up the mountain with it. Esmerelda wants to try it and Phil starts to tire out when she is halfway up and he gives out and she slides back down.
Cro comes across Ivana's wind machine and he realizes that he can use wind power to operate the pulley system. It works for the Neanderthals and when a curious Mojo tries it, it strains to pull him up and he has to let go. Ivana shows Cro that if he switches to a smaller wheel it will pull Mojo up and if he uses the larger one, it pulls up the Neanderthals faster. Soon everyone is enjoying the device and skiing down the slope.
Earl thinks the device is evil since it is interfering with the mammoth's wood gathering. He goes up to try and destroy it and he causes an avalanche. Pakka and Cro save him by putting him on a sled and they go down the mountain. Earl realizes that it is fun but now they don't have enough wood. Cro has another idea. They use the pulley system to get up the mountain to gather wood and use the sled to bring it down. The annual hot tub tradition is saved and Cro receives praise from Earl for his invention.
Back to the present, Mike and Phil return with the plans to find that Doctor Cecelia has built the windmill to power the Christmas lights.