In 1350 Dirk van Herlaer ordered Castle Ammersoyen to be built along a branch of the river Maas. In 1386 the van Herlaer family lost Castle Ammersoyen to the duke of Gelderland who captured the strategically situated castle. The Duke gave the castle to his illegitimate son, who sold it to Johan van Broekhuyzen, Lord of Waardenburg, in 1424. In the next four hundred years Ammersoyen only passed into other hands by inheritance. Under the succeeding five generations of this family Castle Ammersoyen was given its final structure. The poor Clares moved into the castle in 1876 and ended a period of more than five hundred years of private ownership and the castle now became inaccesible to the outer world. In 1957 the Gelderland Castle Trust bought the decrepit castle, started an extensive restoration two years later and completed the work successfully in 1975. One ghost, dubbed "The Lady in Bleu" has been experienced by several people. Two Argentina Ladies once felt the presence of a young couple, supposedly buried under one of the castle's bridges. There has been talk of the ghost of a vicar of Hedel (a small town next to Ammerzoden), making his presence felt within the walls of the castle. He died within Kasteel Ammersoyen.

The investigation began with Derek's walk-around, where he impressively picked up on some specific information about the history of the castle, all of which could be verified. He connected with the death of former owner George Van Arkel, who died in a fire at the castle, as well as his descendant Thomas Van Arkel, suggesting that both their spirits are active in the building. Derek also picked up on previous raids by Spanish and French armies, as well as the use of the castle during World War II as a shelter. Most significantly Derek correctly suggested a connection with the Catholic Church and a Convent of Nuns, however he also revealed a sinister murder of a Priest, who he felt had an illicit liaison with the head of the order of nuns, culminating in her poisoning him and disposing of his body within the castle (an area now blocked up). He also correctly felt that the Cellar had once been used to house washing machines, knowledge of which is extremely scarce. As the night vigils began the team split into smaller groups, and little of any significance occurred. On one occasion Karl noticed that a chandelier was swinging, seemingly of its own accord, however it must be noted that it was connected to a rope on the wall which could easily have been knocked. During Yvette's vigil with Ciarán and Tom she seemed to get two small knocking sounds in reply to her own knock on a table, however she also felt it may have been Ciarán accidentally knocking underneath the table. A single orb was captured on camera, while numerous attempts at table tipping in the South East Tower proved to be uneventful. Even moving the table to the room where the Lady in Bleu was supposed to reside brought little activity besides the occasional knocking sound.