D&D 5E Detect Thoughts as an interrogation tool

[DemoMonkey]

except for this line.... and the corpse is under no Compulsion to offer a truthful answer if you are Hostile to it or it recognizes you as an enemy.

Yes yes, everyone. I know that. I've read the spell description too. You know that. But is only relevant if the person you are interrogating knows that fact.

If they don't, telling them "We will murder you and get the answers from your corpse" should be very motivating.

(Even, "We will murder you and TRY and get the answers from your corpse. Maybe you will be more cooperative dead. Maybe not. Regardless, you'll still be dead."

 

[Mort]

Another option with this is to base the information the mind reader gets is based on the level of success of the saving throw. Fail it by a lot and they get the details. Fail it by a little and they get a solid clue. Succeed by a little? They know they didn't get the answer. Succeed by a lot? False answer.

That's not a bad idea,

You'd have to give a save for surface thought reading though - which the spell currently does not allow.

 

[Oofta]

That's not a bad idea,

You'd have to give a save for surface thought reading though - which the spell currently does not allow.

Yeah, I'm assuming someone that's being interrogated in a world with magic that's also had at least minimal training in how to hide surface thoughts. Of course it depends on who's being interrogated, do they really know who the boss is and so on.

 

[Quickleaf]

PCs have the baddie tied up and questioning him while the bard has Detect Thoughts going. What is the difference between surface thoughts and deeper probe that should allow a save to resist? They're asking him detailed stuff, such as "Who do you work for?" The baddie doesn't want to answer them, but of course he thinks "Mr. Redbeard." Said baddie is also a wizard familiar with magic and knows the PCs have magic.

To answer what the NPC is thinking about in its surface thoughts, you really have to get inside that NPC's head and have the specifics of the situation in mind. I disagree that it's a foregone conclusion that a NPC's surface thoughts would go to their employer's name if asked "who do you work for?"

Certainly, if the NPC was personally close to their employer like a friend, family member, lover, long-time business partner, or something, then that would make sense.

But again, this is one that I really delve into the specifics of the scene. I'm not going to convincingly relate what's on that NPC's mind unless I can really understand their head space first. Tell us a little more about the specifics. Who is the NPC? Who is Mr. Redbeard? What's their relationship?

 

[Nebulous]

I also like to look at it from the other side: if the PC wizard was interrogated, suspected they had magic, and they asked him: "Where are your allies?" He knows they're at the Blue Fart Inn, but is that a surface thought they find? Does the PC get to argue I'm guarding my thoughts and I get a save to end the spell? Does the PC say I'm reciting a jingle endlessly in my head so they will never detect my thoughts for the next 60 seconds....

 

[Nebulous]

But again, this is one that I really delve into the specifics of the scene. I'm not going to convincingly relate what's on that NPC's mind unless I can really understand their head space first. Tell us a little more about the specifics. Who is the NPC? Who is Mr. Redbeard? What's their relationship?

The NPC is someone they've long sought and he does indeed work for Mr. Redbeard, and would not want that known. The two are up to some dastardly no good together and those meddling heroes could ruin it.

 

[Quickleaf]

The NPC is someone they've long sought and he does indeed work for Mr. Redbeard, and would not want that known. The two are up to some dastardly no good together and those meddling heroes could ruin it.

That really doesn't give me much to go on. I presume you're looking for a more general answer about how we use detect thoughts in our own games, rather than advice specific to your scenario?

Here's an example from my old game:

Bard PC used detect thoughts to gauge what a guard leading him to a secret meeting with the queen was thinking about, suspecting this particular guard after a sour interaction between guard and other PCs.

This guard was torn about recent shake up among the royal guard, as several of his brethren were mustering behind the banner of a new commander loyal to the queen's evil son who sought the throne even as his father lay dying. On one hand, guard had sworn to follow his commander and viewed the dowager queen as an unsuitable ruler (cause prejudice / realpolitik paradigm), but on the other hand he genuinely despised the evil prince-who-would-be-king.

Secretly, the guard was leading the bard PC into a trap. The evil prince learned about the secret meetings the PC was having with his mother and sent a false message to lure the PC into the trap.

Bard PC guided conversation towards the guard's opinion on politics for the throne, trying to suss out whether the guard was friend or foe.

I narrated something like this for his surface thoughts: "A soft indecisive queen or a treacherous murderous heir? I'd rather not choose at all. Asking me like I have a choice at all. Mine is to serve and I'm sworn to serve Commander Valense. Perhaps this sycophant deserves the blow back from the high council that is coming his way."

Even with the leading question, it wasn't enough to give an obvious answer about which side this NPC guard supported, nor was it obvious that there was a threat. However, at the time if the player had read into just a little more, been just a little more alert, he might have picked up on some (very subtle) clues I was dropping:

• At that time, the players strongly suspected Prince Ardein had murdered a couple people, but that wasn't common knowledge. In fact, the "murderous" part of his surface thoughts had to do with the trap he was leading the bard PC into.
• The players previously knew that Commander Valense had sent his wife to stay at Prince Ardein's summer estate, and they saw him visit the prince's box during the Tourney of Flowers, so I wasn't exactly hiding that Valense had become loyal to Prince Ardein.
• The "blow back" from the High Council could refer to a previous game session where the High Council denied a motion to censure (initiated by PCs and their allies) Prince Ardein, however that was kind of above this guard's pay grade. This hinted that he'd been led to believe that the trap for the bard PC came from the High Council.

Anyhow, the player didn't catch the subtle cues gained from surface detect thoughts, and didn't want to probe deeper. He got ambushed, used a reaction invisibility power and fled for his life. After the fact, he started connecting the dots and groaned.

 

[Shiroiken]

I generally break things down into 3 groups: the unfamiliar, the prepared, and the trained. Most people are unfamiliar, easily manipulated into giving up information, with the caster making a few Wis/Insight checks to direct the questioning. Those aware of such magics are prepared against them, and can make Wis/Insight checks to avoid accidentally giving out information. A rare few have been mentally prepared against such magics, such as the agents of the Scarlet Brotherhood, and they can make Cha/Deception checks to give out false information instead.

The latter should be rare, but can be a lot of fun. My group in Saltmarsh found the mastermind behind shenanigans threatening to rip the town apart, and he was trained against their tricks. It took about half the session to interrogate him as he kept messing up their Detect Thoughts spells. Unfortunately he eventually failed against the Read Thoughts ability of the Knowledge Cleric, and the no-saving throw Suggestion that followed was his undoing as he was instructed to tell them "completely and honestly, everything about the Brotherhood's plans in Saltmarsh."

 

[Sword of Spirit]

So there is no save unless the spell is probing past surface thoughts, and the question is just, “can you disguise your surface thoughts?”

Sounds to me like we can forget about the spell for a moment and address that. As a DM, if I had to decide if someone could disguise their surface thoughts, I’d call for an Intelligence (Deception) check, DC based on how much of a deception they are attempting. If they succeed, that‘s what you get with a spell that reads surface thoughts.

If you probe and they fail their save then the results of that check are irrelevent because you‘ve magically probed deeper.

 

[Lanefan]

Only if they don't know speak with dead doesn't compel truthfulness.

Heh - we have it that it does: the dead can't lie.