In this follow up to Chariots of the Gods Daniken looks for evidence of aliens' past visits to earth by examining archaeology. Many cultures from the past show rays projecting from the heads of the people they portray. Large carved rocks are hard to explain. Using technology of the time they would have been very tedious to erect.
Throughout the book Daniken asks, "How could they do this without help from aliens?" or "Is this a carving of an alien?"