The plague was devised by King Ahlsendar with the Guild of Writers and Guild of Healers, planning to use it as a biological weapon in the case of emergency. After the Pento turned against Ahlsendar, he ordered to deploy the disease, which resulted to the extermination of the Pento, including to Ages the Pento linked to.
Ahlsendar publicly assumed responsibility and enclosed himself in the Temple of the Great King along with infected Linking Books. After Jolatha secretly broke the seal, the plague escaped, and its signs appeared in the early reign of King Gan. The Guild of Healers would discover that the plague was an evolved version of Ahlsendar's disease. It cut D'ni life spans in half and caused massive infertility. For the elderly and the young, death usually came quickly in the form of heart failure.
The Healers and the Chemists, were working hard to find a cure, even writing Healer Ages hoping to find it elsewhere.and King Behnashiren was of no help and in some of his speeches he accuses the Guilds of "shallow efforts" and "failing their own people." Most people to turned to religion seeking trust and hope. Many factions and cults were created, with messianic figures and healers. Those who held faith that any cure existed outside of miracles and/or special potions were few and far between.
Though some did live through the illness, there was a 95 percent fatality rate once the disease reached its later stages. The plague ended up killing over a quarter of the D'ni population, especially the young and cutting birth rates in half, until its cure was found in 2262.
Behnashiren succumbed to the plague without a heir and was succeeded by Hemelin who encouraged the Healers to search the Healer Ages. After the discovery of the Book of Birenni, a drink was developed that prevented the body from contracting the illness even when directly exposed. Six years after the discovery, the Guild of Healers, led by Guild Master Jaysem, considered the plague cured. A new-found optimism spread throughout the culture, and unofficially, the D'ni Renaissance began.