TVLine.com reveals that the episode, titled "Kent," will take place in the same alternate world that Clark visited in the "Luthor" episode.
In "Kent," our Clark will visit the alternate universe after evil Clark Luthor tricks him. While in the alt world, our Clark will be mistaken by Jonathan for the now-unmasked Ultraman. Jonathan will decide to take justice into his own hands. In the alt world, Jonathan is broke, homeless, and is not in a relationship with Martha.
In the meantime, Clark Luthor will visit Tess in "our" world. He threatens her by saying that she has to either side with him or die.