what does tom and huck witreness in the graveyard

After remaining in the same spot for quite some time, the boys finally hear the sound of muffled voices from the other end of the graveyard, confident that devils are approaching them. But to their surprise, they recognize the voices as the figures come closer and closer!

The voices belong to Old Muff Potter - the town drunk, "that murderin' half-breed" Injun Joe, and young Dr. Robinson. By the light of their lantern, Tom and Huck make out what appears to be a grave robbery. Injun Joe and Potter dig up the coffin and remove the body as Dr. Robinson directs them. Just as the corpse is placed in a wheelbarrow, Muff Potter demands more money from the doctor, who refuses to pay any more. Injun Joe intervenes threatening the doctor with his fists. "You done more than [pay us]," says Joe, recalling how five years ago Dr. Robinson had turned the Injun away from his door when he was asking for food. With revenge on his mind, Injun Joe shouts: "And now I've got you, and you got to settle, you know!"

Dr. Robinson is quick to strike Injun Joe to the ground, after which Muff Potter tackles the doctor to the ground. The doctor flings himself free and strikes Potter unconscious with heavy headboard of the grave. Seeing his chance, Injun Joe grabs the knife Potter had dropped during struggle and stabs the doctor in the chest. As the fatally wounded doctor falls over Potter, Huck and Tom run away in fright.