The Great Perfection, also known as the Atiyoga or Dzogchen (rDzogs chen), is a tradition of esoteric Buddhism that propounds instantaneous enlightenment and was first brought to Tibet in the Eighth Century of the Common Era. The Indian manuscripts of this tradition have been lost in time. Only the Tibetan translations remain. The original teachings of this tradition are contained in Tantras, which are generally divided into three categories: The Mind Section, the Space Section, and the Upadesha Instruction Section. The Upadesha Instruction section is devoted to the pointing out instructions or practical advice in the understanding and application of the Great Perfection. It is generally described as having seventeen root scriptures. The Pearl Necklace Tantra is one of these seventeen works.
In this Tantra Hayagriva, the King of the Wrathful Ones, presents Vajradhara with hard hitting questions about the structure of reality and the nature of the awareness, how we are ensnared and how we are liberated. The Tantra is a frank discussion of the applicability of the great perfection to a world that is wrapped in delusions.
I have included images of the Tibetan manuscript for your convenience and to help preserve this ancient literature.