Muff Potter is a huge part of the plot in this book. When him and his "pard", Injun Joe, are hired by Dr. Robinson, an argument and fistfight erupt. Muff is knocked out while Injun Joe stabs the Doctor in the back. When Muff comes to, he is told that HE killed the Doctor, and believes it. He runs away and takes to hiding, which just increases the villagers suspicions about him. He is eventually arrested after Injun Joe confirmed the suspicions of the villagers.Tom and Huck, being the only ones who know the truth, feel awful but are scared for their lives if they tell the truth. To alieve their consciences, they bring him food, clothes, blankets, etc. When Muff's trial finally occurs in the summer Tom tells the truth and saves the life of Muff. Before he could be arrested Injun Joe runs out and goes into hiding. After this point Muff doesn't show up at all.