Bava Kamma 103: Much Ado about a Bunch of Flax

A story used to assess halakhic stance: flax that is purchased, but not acquired, and then appreciates in value, and the shopkeeper sold it, with the intent to give the money to the original owner (Rav Kahana, in this case). What are the implications for ownership, interest, and the rights to the flax? Plus, how this can come to smack of robbery... Also, a new mishnah, where a thief swears falsely about what he's taken, and therefore has to pay a fifth above the principle he must pay back anyway.