That night, Tom Sawyer sneaks out of his house and finds Huck waiting with his dead cat.
The boys make their way to the graveyard, an old, scary, unkempt plot of land dotted with sunken, crooked graves. It's a spooky place.
After they find the grave of the outlaw, Tom and Huck debate the ethicality of their plan, when they hear strange sounds in the distance.
Soon, they see "devil-fire" and the outlines of three "devils." Turns out it's "that murderin' half-breed Injun Joe," the down-on-his-luck drunk, Muff Potter, and the young Doctor Robinson (9.38).
Joe and Muff are out to help rob the grave for the doc (what kind of experiments he needs it for we never find out), and they have the tools to do it, but once they remove the body they try to get some more money out of him – apparently Injun Joe bears some kind of grudge against the doctor.
When the doctor cries foul, Injun Joe threatens him; Doc Robinson knocks him to the ground with one punch, then starts wrestling with Muff Potter.
While the two men are on the ground, Injun Joe gets up and picks up Muff Potter's knife.
After Robinson breaks free from Muff Potter and hits him with the headboard from Hoss Williams's grave, knocking him out, Injun Joe stabs the doctor in his chest.
Then he puts the bloody knife in Muff Potter's hand and waits for him to come to.
When he does, Joe tells him that he, Muff Potter, stabbed the doctor. Muff, the poor drunk that he is, believes Injun Joe. He asks Injun Joe to keep his mouth shut, and Injun Joe agrees.