In Chapter 4: Gracklstugh of Out of the Abyss, my players are supposed to catch Droki. But they just can't do it.
The party is comprised of a Drow Ranger, a Firbolg Druid, a Dwarf Paladin and an Aasimar Warlock, all level 4. They're currently in the Whorlstone Tunnels where they failed catching Droki once after having twice failed in the city.
From what I understood, Droki is supposed to be roleplayed a bit like the White Rabbit of Alice's Adventures in Wonderland. According to that, I make him flee upon feeling a danger. The fact that Droki has boots of speed1 is the main issue here as he keeps running when the (noisy) adventurers encounter him. I don't want to hand Droki over to the party, but they don't even try to get him anymore. They seem to think that I am making it impossible for them to catch him. The one time they had a half-decent idea (bombarding him with arrows and spells), they had a sequence of bad rolls.
At this point, all I can think of is providing them with one or two potions of speed and specific spells as loot. But maybe there are other ways which I haven't thought about. This has been a challenge for me for two sessions already and I'd really like them to catch the Derro in the next session.
What needs to change?
I'm ready to change the way I handle Droki in order to do so. I have already thought about something like "oops, Droki used the whole of 10 minutes of speed" which has my best favor currently, but as I said I don't want to simply hand him over.
How can I let them catch the NPC without it being a giveaway?
Even further to be helpful to further DMs, how should the Droki situation be handled in Out of the Abyss, normally?
1 double walking speed, opportunity attack rolls on the wearer have disadvantage