The Unfound Door is one of the magical doors that Roland and his ka-tet come across while seeking out The Tower. Out of all the doorways to other worlds they run across, this one is the most powerful and most influential.
Its appearence is very similar to the Beach Doors of the Western Sea. It is made from ironwood, stands about 6 1/2 feet tall, the knob is made of crystal with a rose etched on it and appears to just stand with its hinges attached to nothing but air. The main difference is that instead of High Speech lettered on the face of the door, it has hieroglyphs that mean "Unfound", same as on Black Thirteen's box.
What makes this door so important and powerful is where it can lead the user. It has an unlimited reach, taking the user to any where and when they desire. The trick is that it can only be opened with Black Thirteen, Maerlyn's most dangerous of the Wizard's Rainbow.
Throughout the series this door is seen in a few different places.
Doorway Cave/Cave of Voices
The first time the Unfound Door is seen is in Wolves of the Calla.
The door appears in the Doorway Cave, previously called the Cave of Voices because of its "personality." The Cave of Voices is located north of Calla Bryn Sturgis high in the hills. The cave got its name from the Pit of Voices in the back of the cave. Out of the pit come voices accusing who ever enters of their darkest moments, normally in the voice of their loved ones or friends like the pit can hear the voices in the person's head. The name changed once the Unfound Door appeared in the mouth of the cave.
The door appears in the cave at the same time as Father Callahan and Black Thirteen come to the Calla. This is because of Walter. When Callahan first arrives at The Way Station he is confronted by The Man in Black. After a brief exchange Black Thirteen is shoved into his hands and he is pushed through the Unfound Door to the Cave of Voices.
During their stay at Calla Bryn Sturgis the ka-tet uses the door and Black Thirteen multiple times.
- Eddie Dean uses the door to travel back to New York 1977 while Roland holds Black Thirteen. This is for the first meeting with Calvin Tower.
- Callahan travels to New York and Stoneham, Maine to relay a message to Calvin Tower and Aaron Deepneau. This time both Eddie and Roland stay with Black Thirteen.
- Susannah Dean (with Mia in control) goes to New York 1999 and in an attempt to seal her path so no one can follow she takes Black Thirteen with her.
Since Susannah/Mia takes the ball with her the Unfound Door it becomes dormant. With the help of the Manni enough magic is gathered to be able to open it one last time. This last trip does not go as planned and sends the ka-tet to the opposite of where they were expecting.
- Father Callahan, Jake Chambers and Oy follow Susannah to New York 1999.
- Eddie and Roland are sent to Stoneham 1977 to track down Calvin Tower. They also meet kas-ka gan Stephen King on this trip.
Susannah's Unfound Door (The Eberhard-Faber Door)
During the final leg of the journey, Susannah kept having dreams about the door, Eddie Dean, and Jake Chambers. In her dreams, the door looks just like it did back in the cave except for a couple details. Under the Unfound hieroglyphs is written, "The Artist." The door knob is gold instead of crystal, and on it are two pencils crossed with the erasers cut off...just like the ones Patrick Danville has with him. Just a few days before reaching the tower, Susannah has Patrick draw the door. Once his drawing is done, the door appears without the writing below the hieroglyphs and with a plain metal door knob. Even though it is not identical to the one in her dreams, it still opens to her touch. After an awkward good bye, Susannah goes though the doorway.
When she enters it, she finds Eddie once again, and Jake as his brother. Although they are twinners of the real Jake and Eddie, Eddie Toren and Jake Toren, they have been dreaming about her as well. After a short reunion Susannah's memories begin to fade. According to Stephen King, "And will I tell you that these three lived happily ever after? I will not, for no one ever does. But there was happiness.”
Roland's Unfound Door
When Roland reached The Dark Tower he came upon the Unfound Door one last time. This time the door is the entrance to The Tower itself.
The door is made out of ghostwood and banded with black steel this time. Roland lays Aunt Talitha 's cross and his one remaining gun at the base of The Tower and the hieroglyphs on the door change from "Unfound" to "Found."
With this the door opens and Roland enters.