"Your Conversion will bring you freedom. You will return to your homes, mingle with your people, and do the master’s will gladly."
The Conversion Project was an attempt by the Shadow Lord to infiltrate the minds of Deltoran slaves in an effort to take over Deltora. After losing faith in Grade 3 Ols, the Shadow Lord made the project of utmost importance. The Conversion Project used small pale worms with scarlet heads that were small and thin enough to slip inside a human's ear. When inside, the human would be the Shadow Lord's eyes and ears.
The Shadow Lord intended for thousands of Deltoran slaves to be infected with the worms in the Shadow Area. Then, they would be set free and returned to Deltora as his servants. Although they would appear the same as before they were captured, stealthily they would perform the will of the Shadow Lord, infecting more Deltorans while they slept through the worms they took back with them.
After the Belt of Deltora was restored and the Shadow Lord was banished from Deltora, it had its servants round up thousands of Deltorans to bring back to the Shadowlands. There, it began to work on a new, more subtle way of taking over the land. The result was a species of worm designed to fit into a person's ear. This allowed the Shadow Lord complete control over the individual, who were placed into a dreamlike state and were unaware of what their bodies were being used for. However, early version of the Conversion Project resulted in defective individuals, including blindness, deafness, headaches, and incoherent babbling.
When Lief, Barda, Jasmine and Emlis arrived at the Shadowlands to save Deltoran prisoners, the Conversion Project was about to be put into action. The group stumbled upon the Factory pod room and overheard an infected Tira and 3-19 discussing the Conversion Project and her disappointment in the Pern Pod. By this time the Conversion Project had been perfected after much testing. However, 3-19 felt it was taking too many resources and the Shadow Lord's attention. Tira snapped back, arguing that it was due to Grade 3 Ols poor performance that the Shadow Lord lost faith in the creatures. After realising his mistake in question his master's will, Tira responded that the Conversion Project was the way of the future and he would find out momentarily.
After leaving, the group moved forward, eventually reaching a dimly red-lit room in which a metal box sat in the centre, which had been dragged from the larger workroom they had just been through. Despite feeling the evil that radiated from the box, Lief curiously peered over its edge. Thousands of long pale worms thrashed in a bath of red slime. Appalled at what they had seen, the group continued to move forward, just as the Project was to start. There they met Pi-Ban, who had been imprisoned in a cage for the Project, ready to be moved to the Shadow Arena. Tira approached the metal box in the adjoining room, and locked it, as she just received word that the time had come. Hearing the approaching guards, the group hid in the folds of the roof of the cage, and were taken alongside Pi-Ban, to the Shadow Arena.
At the arena, Deltoran slaves were chained up as the worms were about to be put in. Lief, Jasmine and Barda watched on, but were soon captured by the Baks and placed inside the cage alongside Pi-Ban. Hellena announced that the worms would be their gift and explained the Shadow Lord's plan. At this, Lief understood the extent of the Shadow Lord's plan. Hellena intended to demonstrate the conversion on slaves Pi-Ban and Faith and demanded for the covers to be removed. However, at the sight of Lief, Barda and Jasmine, the Shadow Lord reacted and the arena was sealed tight. Hellana order 3-19 to open the Conversion Project, but as he placed his hands on the box, Lief begged him to stop. Lief pleaded with the Ol to consider his position and worth as a servant to the Shadow Lord, reminding him of his fate if he were to open the box. This was to no avail, as the Shadow Lord struck down the Ol and the trapdoor at the end of box flew open.
The worms flooded into the cage, swarming over the bodies of the group. In a desperate effort, Lief took the pipe to his lips and blew a single pure note. The piercing sound grew louder and echoed throughout the arena and the mountains beyond. At hearing the sound, the worms halted, withered and died. One had almost entered Pi-Bans ear when it fell. In the confusion and rebellion by the Deltoran slaves on their captors, Emlis took the Pirran Pipe from Lief and played a melody. When the Pirrans heard this, they spirited the Deltorans to the underground sea, foiling the Shadow Lord's project. After being rescued by the Plumes, Aurons and Kerans and saying their goodbyes, Lief, Jasmine, Barda and the freed Deltoran slaves were spirited to the Del palace gardens.
The worms were able to control the mind of subjects by crawling into their ear. The defective prototypes caused problems with their hosts such as deafness, headaches and madness. However, they were perfected and were able to infiltrate minds with ease.