The video above is the The Witcher 3 Wild Hunt The Great Escape Main Quest Walkthrough and shows how to complete The Great Escape, the quest featured in The Witcher III: Wild Hunt.
The video walkthrough covers the following objectives:
Talk to Yennefer.
Catch the runaway.
(Optional) Ask Zoltan for help.
Meet Yennefer at the bridge into Oxenfurt.
Enter the prison through the well.
Search the ruins.
Find the missing part of the mechanism using your Witcher Senses.
Repair the mechanism and open the doors.
Enter the sewers.
Find the sorceress Margarita.
Get the key.
Search the commander’s body and find the key to the cell door.
Open the cell.
Get out of the prison.
Wait for daylight.