All - Cut into the cavern wall is a small but strong-looking door of iron plates, about five feet tall and four feet wide. Heavy rivets stud its surface, and a tarnished silver rune—Durgeddin’s smith-mark—gleams on the door’s rusted face. The door is locked.

Without the key, the door requires either a DC 18 DEX check with Thieves' Tools or a DC 25 STR check to open.

Kalhala frowns at the door, then turns to Grymar, "Did those crazy little gnome creatures have any keys on them?"

All - For the sake of brevity, a search of the Redcaps' corpses reveals no keys nor anything that any of you would consider valuable.

Lehmani takes a closer look at the rune, studying its surface... "Can anyone Detect Magic?" She asks... "I could be wrong, but my gut tells me there's more to this door than meets the eye. Perhaps there's a key, or some other method of opening the door down one of these other passages."

Lehmani - That is correct, there is a standard looking keyhole below the door handle.

“Hmmm, I’m thinkin that we need to find something else before we can open this door.  I’m a feelin that the Either passage is the way to go.  While you fellers work on this door, I’m gonna check that one out.  If you’re stuck, come that way and perhaps Either can open up Neither, Or… I dunno.  Hah!”  Grymar grins and starts walking that way, wanting to look at a different option.

Kalhala follows behind Grymar, not wanting him to go off on his own.  He chuckles under his breath at the absurdity of the door names.

Zubien joins in the line, following Grymar

Berkarak shrugs and follows.

Grymar - Following the winding passage, you come to a fork that appears to lead to the same large open space. To the left however, the passage continues for about 15ft then opens up to the west before continuing north again.

Map:

Seeing that there are passages that appear to branch in different directions, Grymar moves forward, continuing to look, trying to find alternative paths that are not behind locked doors.  “You fellers have any idea which ways to go?”

Lehmani calls from the back, "Not a clue, my friend. Just use that legendary dwarven intuition of yours. I'm sure whichever passage you choose will be just the one we need." As she says this, she readies her grip on her mace, prepared for whatever danger they're inevitably about to walk into.

This place sure was getting stranger and stranger, Kalhala grips his sword as he follows closely behind Grymar.

Grymar continues to move forward, taking the leftward fork, hoping that it was the less traveled and that it would make all the difference.  

Zubien follows the group, checking their rear to make sure they are not being followed, as well their surroundings in the tunnel (Perception: 17)

All - As you pass the offshoot to the left, you glimpse a small area covered in fungus.

Map:

Kalhala takes a bit of tartan off his sleeve and holds it in front of his mouth, "Don't breathe the stuff in!  My brother once had quite the trip on fungus, it was hilarious until he almost walked off a cliff."  He shudders remembering the time, "and man, once we got him away from the edge, we all had to tackle him in a big ol pile up or he was going to try again!  Stuff makes you crazy!"

He'll continue to follow Grymar unless the dwarf wants him to go first and he happily will.

Zubien will take the advice and cover his nose and mouth to protect himself from the fungus

Berkarak follows suit, breathing into the crook of his elbow.

“Ok, lemme jus look at the opening and peek.”  Grymar takes a deep breath and holds his breath, pinching his nose and covering his mouth, walking 10 feet or so to the west, peering into the room to make sure there is nothing is missed.