Huckleberry Finn's plan to escape from his father entailed cutting a hole in the wall of the cabin. He also killed a pig and spread the blood around the cabin floor and down to the riverbed, to make it appear he'd been killed. He then took off down the river.
Huckleberry Finn's father, Pap Finn, was a drunkard who would often yell at and abuse Huck. When Pap Finn wins custody of Huck, he takes Huck to a cabin deep in the woods. Whenever Pap leaves to fish, or to drink, he locks Huck inside of a closet, and abuses and berates Huck whenever he returns.
Huck wants to be free and independent so he can do the things he wants to do. So, he carefully plans his escape. Huck doesn't want anyone, especially Pap, coming to look for him, so he wants everyone to think he's been killed.
First, he finds an empty canoe drifting down the river, retrieves it and hides it in the bushes. He then cuts a hole in the wall of the cabin from which he can make his escape. He butchers a pig and scatters pig blood throughout the cabin, dragging it down to the river, leaving a trail of blood. He does this so that his father and everyone else will believe he was murdered and thrown into the river. He then retrieves the canoe that he'd hidden in the bushes and takes off down river, making his escape.
Huck is pleased with himself and believes his plan has worked when he sees a boatload of people searching the river for his body. Huck is now on is own and ready to live the independent life he dreams of.