From the WotC plot recap:
The trouble began when the rangers from a distant outpost of Waterdeep found an unguarded treasure in a dragon's lair. "We'll just take a few things," they said. "It will never notice."
- - Teseryne Truesilver
- - Daughter of Talanthe Truesilver
- - Year of Rogue Dragons
The Order of the Jade Blade was wintering in Waterdeep with Jerythi Phalkon after rescuing Otar from a band of crazed Cyricists in Undermountain. One wintry day the adventurers heard a voice whispering to them in their ears, asking them to meet with Captain Rulathon at the Troll Tower within the hour. Recognizing the spell as whispering wind, our heroes went to the Troll Tower as asked.
Rulathon is a captain in the city guard of Waterdeep and a friend of mine. I had mentioned the Jade Blade and their noble deeds to him several times in the past. So when he needed assistance and learned they were in Waterdeep, he called upon them.
Rulathon needed to send supplies to the northern outpost of Swordhold in the Sword Mountains. Unfortunately, a nasty bout of the flux had struck the guards, and he didn't have any veterans to send with the supplies. He couldn't send just anyone, because the Sword Mountains are very dangerous. The Jade Blade agreed to escort the two horses, named Apples and Oranges, and a sled containing a large amount of supplies, such as food, blankets, and other equipment.
The first several days of the journey were uneventful, but one evening when they were closer to the Sword Mountains they were attacked by two large creatures made entirely out of ice. I have since discovered that the beasts are known as chraals and are dangerous elemental creatures infused with the spirit of the wicked and depraved. The adventurers defeated the creatures and followed their trail back to a cave, where they found a pool of water which acted as a gate to the Elemental Plane of Water. The adventurers were unable to destroy the gate but it did not seem to be active at the moment so they rested there for the night.
The next morning they entered the foothills of the Sword Mountains. The heavy snow from the previous evening covered the hills with a thick powder, making it difficult to travel with any kind of speed. In addition, the hillsides were the home of a pair of remorhaz who had riddled the area with their tunnels. Not only did these tunnels allow the remorhaz to travel quickly beneath the earth but they created perilous traps for the adventurers as they waded through the snow. The worm-like monstrosities exploded from the under snow, surprising the Jade Blade. One of adventurers was swallowed by the things and found the red-hot belly of the beast. Fortunately, the Jade Blade slew the creatures before the adventurer inside was burned to a crisp.
The following day, the path dropped down to a wide valley which was filled with a large frozen lake, bordered by sheer cliffs on each side. The path turned away from the lake and continued up a narrow ridge. However, the frozen lake provided a quicker route to Swordhold, which was on the far side. The ice on the lake was very solid and held the weight of the adventurers with ease.
When the adventurers were about halfway across, they found a rope stretched across the lake about five feet above the ice. They were understandably cautious and ducked underneath the rope without touching it. Unfortunately, this set off a glyph of warding inscribed on the ice. The blast not only wounded our heroes, but severed the rope, which was attached to a primed catapult atop the western cliff. Without the tension of the rope, the catapult released, flinging huge stones down onto the icy lake. The ice shattered from the impact, and the Jade Blade watched in horror as the cracking ice spread toward them. While they could easily outrun the cracking ice, the horses and sled of supplies could not. The adventures used magic to haste themselves and Apples and Oranges. The boost was just enough to get the steeds and their cargo out of the reach of the shattering ice.
On the cliffside near Swordhold, the Jade Blade found the frozen remains of a city guardsman from Waterdeep who had been pinned to the wall by a large icicle. Deep gouges in the ice over the head of the guardsman spelled the Draconic word for "thief." Concerned for the fate of the remaining rangers of Swordhold, the Jade Blade hurried the rest of the way.
As they approached the keep, a white dragon with an armored rider landed before the gate to Swordhold. The white dragon was Borealis and the rider was Llianne Rimewind, a favored soul of Auril. A patrol of rangers from the outpost had stumbled upon Borealis' lair while he was out hunting, and they took a few items from the dragon's stash—one of which belonged to Llianne. The dragon and the Aurilite were enraged at the theft and had been hunting the rangers one by one and were determined to pull the tower down and kill everyone inside.
The arrival of the Jade Blade forced the two to deal with them before they could slaughter those in the tower. Borealis made liberal use of his breath weapon while Llianne called upon the power of Auril to fill her as she strode into battle. Dragons are never an easy foe, and the Jade Blade was sorely challenged that day by the icy lake. It made their victory that much sweeter.
The rangers at Swordhold were grateful for the supplies and the rescue from the dragon. They led the Jade Blade to the dragon's lair, where the adventures and city guardsmen plundered the hoard. Fortified by several days of rest and loaded down with treasure, they began to retrace their footsteps toward Waterdeep.