Stealth w/ Advantage: 17

If I can get guidance off as I leave without being heard: 3

Kindra and Mel are able to stealthily move to the guard tower, and up into the armory. They are joined by Eldeth, as well as Sarith Kzekarit, the drow that was imprisoned with them. Other prisoners leave at their own pace, some jumping right down into the webbing below.

In the armory, Kindra and Mel are able to find their equipment, as well as the following, free for the taking:

6 chain shirts
6 suits of studded leather armor
6 shields
6 hand crossbows
20 cases of hand crossbow bolts, each case containing 20 bolts
6 shortswords and 10 daggers
6 bags of caltrops (20 caltrops per bag)
4 100-foot-long coils of silk rope
2 building hammers (not usable as weapons)
2 bags of iron spikes (10 spikes per bag)

Eldeth helps herself to a chain shirt, a shield, and a shortsword and dagger. Sarith takes a suit of studded leather armor, a dagger, and a hand crossbow with some bolts.

Mel will take a hand crossbow/bolts, a shortsword (she has 2 now), a dagger, a chain shirt, and a shield.

Kindra will take a chain shirt, shield, dagger, 2 bags of caltrops, 2 coils of rope, a hammer, and both bags of pitons.

(Is there anything that can be used as an arcane focus, and/or a spellbook?)

(Make a Perception check)

Perception + Guidance at Advantage (Mel is proficient in perception skill so she's helping): 9

"Hey Mel, do you see a wand or anything for spells in there?" she whispers.

Mel lets out a gasp. "You know, I think I do." She picks up a tome with the visage of a spider on the cover, along with a black wand. "It looks like one of our drow friends is a mage-in-training."

(The spellbook has your chosen 1st-level spells recorded in it, unless you want me to pick them for you.)

Kindra grins. "Awesome. Let's bail this place." 

As they move out, Kindra thinks to herself: Gotta get a new cover for this thing. Hate spiders.

(Chosen spells will do fine)

When everyone's ready, she'll jump into the pool after them.