If you're aiming for the best ending in Kingdom Come: Deliverance 2, saving Sam is a crucial task. Here's how you can find and rescue him during the "Reckoning" quest.
Rescuing Sam During "Reckoning"
As you near the end of the main quest line, you'll discover that Sam is being held captive at Praguer's Camp, captured by Brabant. To save him, you'll need to infiltrate the camp, which you can do through stealth or by choosing violence.
To move around the camp without arousing suspicion, you'll need a guard's outfit. You can obtain one by either killing a guard and stealing their outfit (make sure to hide the body), or by looting one of the many chests within the camp. Once you have the outfit equipped, you can freely explore the camp to locate Sam.
Screenshot by The Escapist
Sam is located in a barn on the left side of the camp, beyond the open area with a cooking fire. Use the ladder on the side of the barn to climb up and then drop down inside, where you'll interrupt Brabant. At this point, you have a few options with significant consequences. You can choose to kill or spare Brabant; sparing him contributes to achieving the best ending.
When to Rescue Sam
After freeing Sam, it's not yet time to escape with him. He'll inform you about von Aulitz, who is also in the camp. It's advisable to deal with von Aulitz first, then find a horse, and finally return to Sam to get him out of the camp. Sam will be safe waiting for you, and this order makes the tasks easier since you'll need to carry him to the horse.
Von Aulitz is located in the main part of the camp. Wearing the guard outfit will allow you to enter his area without issue. Upon finding von Aulitz, who is already dying, he'll request a dignified death. Granting this is the most honorable choice, but you can also choose to kill him cruelly or leave him to die slowly. Interestingly, leaving him to die contributes to the best ending.
Once you've dealt with von Aulitz, return to the barn where Sam is waiting. If a guard questions you about moving Sam, simply say you're relocating a body, which should clear any suspicion. Head to the camp gates, exit, and turn right to circle around the camp's perimeter.
Screenshot by The Escapist
Follow the camp's exterior until you reach the stables. Choose a horse, mount up with Sam, and escape, bringing you one step closer to completing Kingdom Come: Deliverance 2's main quests and achieving the best ending.