The Thornwood
The Thornwood is the vast, ancient forest against Westmarch's western wall. For three hundred years the Pact has kept the city out of it and it out of the city: no logging past the old Border Stones that mark the forest's edge, no hunting in the deep woods, and a cleared strip called the Green Belt kept safe between the trees and the wall. The Rangers of the Green walk that line; the Delver's Guild works the near forest under licence.
That was the arrangement. Lately monsters cross the Green Belt where they should not, the mist comes over the wall, and the party has walked far enough into the trees to learn that the forest is a great deal older and stranger than the Pact admits. What the party now understands about why is on The Pact and the Stones.
The Singing Pools
Fey water, three days' march in, kept by Lady Oona and guarded on the approach by the redcap Riven-Vow. The party came for Source Stone, which lies at the bottom of the Pools, and paid Oona's price to get it — Kaelen took on the Sorrow of the Forest. Whoever drinks is shown things: Kaelen was shown the Duke on his knees before a great stone, afraid, speaking of the Great Vow and the lost South Stone. The Fey here believe the Greenwood Pact holds "an imbalance in the bargain," and they know more than they are permitted to say.
Harrow Keep
A ruined fortress deep in the forest — broken walls, a rusted portcullis, a dry well, and a great tree filling the courtyard. It fell during the Green War, and by the party's day it was held by the Poison Scale kobolds, who worship the dragon Verdanthis and believed she laired there. She did not. She had left the Tess-Kydra in the kobolds' charge and gone elsewhere.
The party took the keep, killed Chief Scris, and recovered the Tess-Kydra. In a locked chest they also found the thing that unmade the official history: a letter by Commander Edric Harrow, written in the year 934, admitting the keep never defeated the forest but was forced into a secret treaty to survive — and that Harrow hid the truth so the crown would believe the war was won. And they found a ranger's medallion that had belonged to Mira's lost mentor, Edran Holloway — which raised, for Kaelen, the question of how many senior rangers have walked into this forest and never come out.
Celindara — the lost city
An elven city and a seat of great learning that the Thornwood swallowed whole during the Green War. It is where the Tess-Kydra — and the vessel that mends the stones — was made. Quill found it on old Archive maps: a week or two's march deep, far past Harrow Keep.
Celindara is now the party's next road. The Duke will not stake the city's survival on a single artifact, and has commissioned the party to find the lost city and bring back either a second vessel or the method of making one — and whatever else a place of that much learning might still hold. The catch is simple and large: the maps disagree, and nobody living knows where Celindara actually is. The Archive and the Grove are the places to start.
What else moves in the deep
The Poison Scale. Kobolds who worship Verdanthis, hunt the deep forest, and are forever at war with the gnolls — "dog men" — over its ground. Weak one at a time, dangerous in numbers, and fielding their own spellcasters and poisoners. Scattered now, since Harrow Keep.
The mist. Not confined to the forest any more. It came over the wall into the Greenmark and woke a warded park into something that attacked a market — the same motes of light the party saw in the Warrens, drifting in and turning green things hostile. Mending the Warren Stone stopped it there. The wider problem has not gone away.