Ionmarsh is a swamp near Davenside in Valond, featured in Chapter 1. Ionmarsh is described in Sky's mother's journals as the home of a "hidden temple" with a map which Sky believed may be related to the Old Kingdom. Ionmarsh contains a ruined temple that is clearly the one referenced in the journals. Outside the temple, there's a stone tablet carved with Kadan writing. A puddle of black "goo" also sits in the marsh that Sky and Aida cannot identify.
The temple is a stone building. Its entryway leads down a flight of stairs into pitch darkness, which is alleviated by a switch on the wall that lights up the first room. The first open room features a statue of an old queen. There are also a few more puddles of black goo, as well as a couple gold on the floor. A red jewel sits in the queen statue's forehead, serving as a magical switch that grants entry to the next room. When Aida removes it, the building shakes and Aida flies in the air glowing for a short while. After this, the statue and jewel vanish, and the entryway to the second room is opened.
The density of the black puddles increases deeper in the building, and Aida also developed a greater sense of "being watched." The second room proves to be a dead end, with two black puddles of liquid and, again, a couple coins on the ground. In this room, Aida and Sky are first introduced to Zander and Tillie. Tillie points out that the map that Sky is looking for is actually etched onto the ground of the second room.
- Aida states that Ionmarsh smells like "dead fish and rotten food."
- In Ionmarsh, outside the ruined temple, a dead tree possesses scratch marks that are "too deep" to be left by a wolf.
- Because neither Sky nor Aida can read Kadan, the stone tablet outside the temple is never translated, but Aida hypothesizes that it might say, "Do not enter, there are monsters inside and it smells really bad."
- The black puddles are actually incubi. When touched, they will cause horrible nightmares whose duration varies depending on the age of the incubus. Fully grown incubi can induce nightmares that last for years.
- Zander claims that the black puddles are excrement, but he may be joking.
- Aida touches one of the black puddles in the second room, and is saved by Tillie.
- Zander and Tillie came to view the temple for research.
- The jewel had a lock placed on it so that it was only able to be removed, triggering the entrance to the secret passageway, by certain people. Aida hypothesizes that the lock only admits nobles.