In the last shot of Episode 4, Jaime Lannister is seen plummeting into a lake and possibly (but probably not) dying. It's likely that he is captured by the Dothrakis. So maybe it's time for Tyrion to return the favor and free his brother Jaime from Dany captivity.
The theory would seem to make sense given apparent hints in the preview for next week's episode. Tyrion is being told that he has to find a way to convince the queen.
What do you think about this theory?