When you get to the underground area of the Gerudo Town in Tears of the Kingdom, you will find there is a man locked in the prison cell. If you move the box up to the cage and stand on it, you will be able to speak to him. You can also use this secret to get inside the prison cell to talk to him. He asks you to help him with his daughter Aaqlet and his wife Perda who he hasn’t seen since they came to the town. This doesn’t seem to trigger a side quest that shows up in your journal but it is an interesting mystery. Here is what you need to do.
You will find Aaqlet running around between the cave and the upper parts of the town. When you are facing the prison cell, turn left and head down toward the area that contains beds. You may find Aaqlet here but if not, you will find a picture she has drawn of the wall. This map shows the vendors in Gerudo town and a picture of a woman. This woman is where you will find Perda.
If you find Aaqlet at some point and speak with her, she will tell you her mother is working on a secret clothing shop. The map on the wall is the clue as to where she is. If you make your way down this alley, you can interact with a door but find that it is locked and can’t get inside. You will need to find another way inside.
To get inside, you need to go to the cave below. There are lots of waterfalls around the town that fall into the ground. Jump into one and you will be able to make your way underneath the shop and then uplift to get up inside the store to find the wife.
Speak with the Gerudo woman and she will tell you a bit about her story and mention more about what she has been up to in the Gerudo secret club. You can then return to the guy in the prison and talk to him. Since there was no quest, it won’t be marked as complete but this will be the end of the story for now.
There have been a few other people suggesting that there is a way to reunite Wabbin with Perda and Aaqlet. It would appear that the game designers had originally intended for this to be the case but the quest does not exist in the game anymore. A more concrete ending to this little side story just does not exist for the moment.