Need feedback on what to do with captured pcs.

Tldr. 1/2 party captured by aboleth. How should I play this.

So this is going to be a minute thank you in advance to all who finish it.

My party is at the midpoint uptop trying to help derendils village by figuring out what's wrong with the water and why some people are fleeing.

Turns out there's an aboleth in this water filled cave system that the locals get water from. They went on and found the aboleth with a minor collection of kou-toa some enslaved elves and 2 chuul... the intent was for them to parley and then seeing the overwhelming forces retreat and come up with a plan. However 1 of them decided to try and calm emotions and free a couple elves who were enslaved. He succeeded on saving 2 but it started a fight they were sorely outmatched for.

Session ended with 3 pcs being grappled and dragged into the water further into the cave complex while the other 2 plus a leveled up derendil tried to swim after they were dragged by the current and spat out into a lake. (Think broken arrow escape from the nuke)

So I need ideas on what to do to help everyone.

Currently I'm thinking of having the aboleth have to take off to speak with big bad (I'm thinking demigorgon) and leaving the 3 in captured space with guards. I was also thinking of having a surprise npc be there and to have them try an escape.

Also 3 of the 5 person party are reading the drizzt novels and love them. Was thinking of having the surprise npc be drizzt or Wolfgar who could help with the escape.

Any and all ideas are welcome