My players tried to capture one of my bosses (they didn't know it was a boss) and after a few rolls they succeeded. They started to interrogate him (the NPC is a human) and after obtaining the information they wanted he was stabbed in the chest. Basically, imagine having one of the most powerful warriors of the kingdom killed by a throat cut because the rogue rolled 19 on Stealth.

Now here's the thing: how do I handle realism and one-shotting bosses out of combat? Because I can think of excuses but I don't want my players to feel discouraged or think that their actions are meaningless if the DM wants this NPC to fight them.

Adapt and move on

Players do have a tendency to ruin the best-laid plans of the DM!

In your scenario, I wonder if maybe there was a mistake somewhere that allowed such a powerful NPC to be captured and made helpless in the first place. Typically you would not expect such a character to be walking around alone and defenceless in the first place.

But what's done is done, so now you may need to adjust your plans. Bearing in mind that your players (hopefully) don't know your entire plan.

So, perhaps this NPC was not the big boss after all. He was actually an underling, a front, the right-hand man and so on. He may even have put up the pretence of being the boss to act as a diversion to the real guy.

Assuming the players didn't take measures to prevent it, his body could always be recovered by his own allies and raised. (Possibly the simplest answer).

Or maybe the NPC could end up returning as an undead, even meaner than before!

Or another NPC, one the players have not encountered before, could take over the boss's criminal organisation. You could even have multiple criminals and/or monsters fighting to take over the criminal enterprise and causing your plot to veer off into a completely different direction!

Note: All of the above could be in addition to the points made in SaggingRufus's answer.

Your PCs are acting as vigilantes, and as such that should come with the consequence of murdering someone.

I can think of a few ways to handle this off the top of my head:

1. Have the local authorities (ex: town guards, military, city watch) come after them and launch a full investigation into the murder of this NPC


2. Have the rest of his gang find out that the PCs murdered their boss. Maybe there was someone in that gang looking to have the Boss killed so they could rise to power.


3. Have the rest of his gang go a on quest to attempt to resurrect him using relics that the PCs need to collect before they do.

Either way, you can use this as a way to change the story.

I agree with adapt and move on, but an alternative is to

look at what the boss has up their sleeve to prevent this

An intelligent enemy won't put themselves into a situation they don't think they can escape from, so maybe he is a magic user and "You reach for your dagger and as you strike the captive vanishes, he reappears seconds later in the corridor, turns and runs" (IE: Casts Misty Step as a reaction).

Maybe he is a hardy barbarian and "You push the dagger into his chest which resists like it was made of steel! A small dribble of blood runs out where you would expect a flood. Suddenly his muscles tense and he breaks free of his bonds!" (IE: Bear totem resistance to non-magical piercing, followed by raging and gaining advantage on strength checks to break the ropes / manacles).

It might be too late for you to do this now, but equally if your PC's were taken captive I don't think they would like to be killed like chumps, so can probably understand the NPC's not going out this way. Your boss would still be unarmed, unarmoured and at a serious disadvantage, but at least he would have his HP and actions to make his escape.

Serial outcomes to BBEG's execution: Revenant and/or Deputy

If you look into the Monster Manual entry for Revenant, you'll find this opener:

A revenant forms from the soul of a mortal who met a cruel and undeserving fate.

Whether the BBEG met a fate as characterized there is up to you as DM to decide, but as the party continues with their adventure they will eventually discover that they are being tracked by a Revenant. Or, the Revenant will make an entrance at a key moment with the stabber squarely in his sights.

Meanwhile, since the boss has been taken out ...

BBEG's deputy takes over

You don't miss a beat in the adventure. Your BBEG's right hand man/woman was looking into {something} concerning their criminal/evil/nefarious enterprise. As with various criminal organizations, once the top dog is gone Number Two takes the reins. Granted, you can let some time pass as this equally nasty opponent consolidates power within the bad guy group, but it's not that hard to drop hints that the bad things the BBEG's people were up to are still going on, or begin to go on again, with a slight change in style. (A different sign or letter is carved into the foreheads of assassinated foes of the organization, for example ...)

You can combine both of the above if you think it will fit the challenge and narrative for your party. Not only did Number Two take over (who now has an eye on how deadly the party is, and how ruthless the PC's are) but also the Revenant makes a grand entrance at a critical point.

Improvise, Overcome, Adapt. Gunny Highway's guidance applies to DMs as well as to Marines.

If it hasn't happened yet, you can retcon.

As a GM, you have a "spoken" or "unspoken" agreement with the players. You set challenges, they solve them, your world is consistent and they have agency -- their actions matter. So if they defeated the Big Bad through quick thinking and a few lucky die rolls, they deserve a reward.

On the other hand, you are free to change any element of the game that hasn't happened "on stage" yet. You are not required to make a plan before the campaign starts and to stick to it, no matter what. Some options how to cheat and adapt:

• Reorganize the "chain of command" of the NPCs. The slain warrior was only the second-in-command, and you introduce a new Evil Overlord. Either this new boss is weaker than the old one, or the players are rewarded in some other way for their success.


• The slain warrior was the Big Bad, but with his disappearance the former second-in-command makes a move. Again the new boss is not quite as capable as the old one.
  
  
  
  
  • As a variant, the Big Bad's conspiracy comes apart and new, different adventures happen. Send the players to secure the magic items in the slain warrior's arsenal, fighting a hundred brushfires rather than a big fight.
  
  
  
  


• If that is consistent with the information from the interrogation, decide that the slain warrior never was the Big Bad after all. He was a third party in the conflict, trying to profit from the mayhem in some way. That explains why he knew things, and it doesn't retcon him into an innocent.

Think through the clues that were handed out so far. Come up with a "new truth" consistent will all those clues. The slain warrior will be somewhere, but not necessarily on top of the pyramid.

Side note, as a GM you are allowed to cheat even in combat as long as you keep faith with the players. If cause-and-effect principles are violated, it follows the narrative logic. You deliver a fun challenge, they solve it. The actions of the NPCs affect the setting, and so do the actions of the PCs.