The atman (soul), in the Eastern belief system, is eternal, immortal. The phenomenon of (physical) death is, thus, nothing but its disembodiment and its 'reincarnation' in a new body. And what determine as atman's choice of a new body is the law of karma -- the merits and demerits of one's actions in the present life.
The notions of karma and reincarnation constitute the fundamental tenets of Indian thinking; though these, like many other doctrinal beliefs, are hard to prove/disprove in purely rationalistic or even empirical terms. Swami Muni Narayana Prasad looks afresh at these age-old doctrinal beliefs -- from the viewpoint of an Advaitin (non-dualist), developing stimulating insights from his studies of the Upanishads, the Bhagavad Gita the Brahma Sutras and, these besides, the works of his mentor: Narayana Guru. Contextually, among other questions, his book also dwells on Ultimate Reality, Birth and Death, and the Two Paths: Devayana (the path of gods) and Pitriyana (the path of manes), which either the souls take to after death.