Caalorne is an Altmer traveling alchemist. According to dialogue, he was ambushed by a local group of argonian bandits, who stole his potions. These potions are essential to an important trade deal between House Dres and the Darkvale Trading Coster, of which he is a member, and he will reward you for retrieving his goods.
The bodies of the dead mercenaries hired to guard him on his journey to Kragenmoore can be found all around him, along with the remains of the cart he hid under during the ambush, which is how he alone survived the attack.
The bandits can be found hiding out in Sheogorath's Tongue, not far from where Caalorne is.