(Literally the cutscene from the game. He is so bbg)

The werewolf stands atop the foot of a small cliff, overlooking the Dragonborn with the red moon behind the creature, reflecting an eerie glow throughout Bloated Man’s Grotto

With your weapon drawn, Sinding, a man of whom killed a young girl during a full moon and was prisoner within Falkreath, snarls and speaks;

"...You! Why?"

Will you Kill him and join the other hunters strewn about the cairn, or will you join Sinding and help him destroy his potential killers?