The Rescue
The party avoided the sleeping gremlins, and followed the traces of blood by another path, until they reached a cave containing multiple gremlins.
Gral flanked the cave, and once he was in position, Aegir moved into the cave to attempt diplomacy. The gremlins immediately attacked. During the fight, Gral got trampled by the shaman and another gremlin fleeing, and though he followed them for a bit, decided to return to the group when they approached the sleeping gremlins. Aegir and Bremor handily defeated the other three gremlins.
Once the fight was finished, the missing goblins appeared, having barricaded themselves in an ancient tomb which the gremlins had been guarding for these past few days. The group found a number of treasures in the tomb, which they decided to take with them.
Leaving the Gremlin caves was managed without much trouble, except for a throwing spear from an ambushing gremlin which withdrew immediately after its throw.
The Return
On their trip back in the main tunnel, they were followed by a humanoid capable of camouflage and wall-crawling. Gral tried leaving it a ration, and the creature seemed to like it, revealing itself to the party, though either unwilling to let them get close or just copying their movements, so that it moved back whenever they moved closer.
Returning into the tunnel carved by Tzork's men, they decided to make a forced march back to safety, rather than risk sleeping in the staging post. Once back to safety, the party members received a load of thanks, and then each retired to bed; Gral with his family, and Bremor borrowing a guest room at Aegir's family home.
Next morning, after sleeping for 12 hours, Gral's mother showed concern that he had come home with a stab tear and blood on his clothes, while Aegir's father was concerned that he was hanging out with a member of the Dark Dragons.
A New Mission
A bit later in the day, they met up with Tzork who gave them their reward (some silver and a bunch of assorted items), and purchased a magical chest from them which was part of their tomb loot. He also expressed interest in whether they had found more of the type of gems that was on the chest (Gral secretly had), and a willingness to buy them.
Finally he offered them another job to escort another expedition into the underground. The group accepted.