So, your players have finally found someone who knows about what happened that night in the temple. The bard is asking some pretty sensible questions, and the dice are behaving themselves. You take a look down at your campaign notebook, and wonder how much of your painstakingly crafted web of behind the scenes intricacies to reveal.
You want the conversation to be worth the players’ time, but it should also feel natural - you’d also quite like the witness to stop short of revealing the Lich’s entire succession plan.
This is what I like to do : give the NPC, as small useful part of the story and let them talk about it properly. Let the group have a conversation that can move the adventure forward while also leaving plenty more to uncover.
Give the players a satisfying taste, but also leave them hungry for more.
The trick is keeping track of where each NPC’s view of events begins and ends.
Give the NPC a smaller part of the story
Suppose it was the bronze bell that was stolen from the temple. The party visit Nell, who runs the river ferry. Before dawn on the night in question, she thought she heard the bell’s familiar cracked note coming from a passing wagon as it disembarked from her ferry. She then saw it head north along the towpath.
But Nell has her own problem : she had taken the wagon across outside of her licensed hours for a suspiciously generous tip. Reporting the theft could lose her her livelihood. She had never met the customer and has no idea why anyone would want the old bell from the temple.
Thats enough to drive the conversation. Nell can describe the wagon, be slightly cagey about why she carried it, and then draw a blank when asked about where it was heading. Those answers all belong specifically to Nell, that's where the scope of her experience begins and ends.
In terms of notes to keep - Nell doesn't need a biography, just a short note
Covered wagon, north towpath, before dawn. Heard the stolen bell. Took illegal fare and now worried about losing her licence. Doesn't know who the person was driving the wagon.
If we need to, from this we can easily flesh things out further. Running the ferry gives Nell a reason to notice how heavily loaded the wagon was. If the players ask if the driver had a crest on their coat, we can take a moment to decide if she recognises it, and why. She might know it from other passengers and conversations with them, or she might just recognise the shape. Either answer can be a lead for the players, but neither gives her a reason to know what happens when the bell reaches the distant ritual chamber.
You can always improvise, but the trick is to have an idea of how she would have learned an answer before putting it in her mouth.
Decide what the roll can win
Before asking the players to roll, clarify their intent. Are they trying to get Nell to describe the wagon, admit she ferried it, or lend them the boat? Those are different flavours, with very different things for her to be persuaded to agree to.
The 2024 Influence action highlights the difference between a creating being willing, unwilling or hesitant about a request. The hesitant case calls for the ability check, the willing and unwilling ones resolve without one. This can let you decide if dice rolls have a place in this encounter at all.
For this scene, I’d have Nell freely share the wagons’ description and direction. But she’d be hesitant about mentioning the time because of the risk to her licence. If the party persuades her to give a full account, that success should become useful to them. She should explain that it happened out of hours before dawn, and that she is sure she heard the familiar sound of the cracked bell coming from inside.
That last detail changes what the party can reasonably conclude. They have a a witness to the bell’s journey, rather than just rumors of a cart leaving town by dark. They can decide to pursue north, or take their new knowledge back to the temple.
If they ask who paid for the theft, Nell has no idea - she should say so plainly. Then give the successful conversation something else it can logically produce. Maybe Nell still has the unusual coin she was paid with, and might be willing to hand it over. You can also establish these further details while preparing the scene - this means Nell can indirectly reveal more information that she actually knows herself, and give the players something to take elsewhere.
A player who is invested in Persuasion deserves a worthwhile chance to apply it. Give them a reluctant witness who can offer help, and let winning that help matter to the story. You shouldn't need to add unrelated secrets to reward good roleplay or rolling.
A helpful witness can have a blank spot
There's also a tiring version of these scenes where every answer sends the party to someone else. The ferryman suggests the merchant, the merchant thinks the priests will have an idea, and the priest recommends a sage three days away. The players are just filling up an address book and still don't know what's happening.
Before sending the players anywhere else, consider what this NPC actually has to answer. Nell can point out the towpath on their map. She can describe the landing spot, so if the party chooses to follow, they have enough to go on.
Her missing knowledge can then become a specific question for later on : who uses these coins? Where could the wagon have left the towpath? The players can choose to investigate - they are driving their own story. They don't have to finish a circuit of interviews before they can make their own choices that matter.
Be equally clear when an NPC is guessing. Nell might suspect smugglers because of the fare and the hour. Describe the observations that led her to this suspicion. If she simply announces that smugglers stole the bell, the party might treat that as something she, or you as the DM know to be true when it isn't.
And if she doesn't end up telling them about the coin, keep the facts that have already been offered. The party still knows about the wagon and the towpath. Their next move might be less informed but they still have something new to go on.
Give the next scene a head start
It can be tempting to protect a later scene by keeping some information out of reach. But finding out about a danger beforehand can be the start of the fun. Once they know the bell went north, they can argue amongst themselves about whether to pursue, inspect the landing spot, or go back and involve the temple further - that's something for them to write their own story with.
If you want Nell’s cooperation to pay off beyond the immediate leads, give her a useful offer. Maybe she offers to lend the party a skill and show them a side channel heads in the same direction of the towpath. The skiff could potentially get ahead of the wagon, but they'll have to leave their horses and some of their equipment behind. Following on foot on foot lets them examine the trail closely, but at the expense of time.
Then end the conversation and ask them what’s next. It’s their story as well.