I am surprised this book is not better known, because it is not only Hammond Innes's most complex and literary book, but an excellent novel in any company. It is concerned with the origins of man and with early man's similarities with his modern counterpart, and has a troubled father-son relationship and a tense cold war backdrop.Pieter Van der Voort has a theory that Greece was where the earliest humans first settled in Europe and is exploring caves on the island of Levkas to try to find evidence of early man. He is obsessed with his theory, rival academics seek to take credit for his discoveries and the Greek authorities are unhelpful, thinking he might be a Soviet spy as he had worked in Russia.Paul Van der Voort, his adopted son and an ex-sailor gets drawn into his father's affairs. They are very different people and not close; the relationship between them is shown well. Pieter is, appropriately perhaps, closer to his early humans than he is to his son. The finale in the Levkas caves is masterful and also typically Innes.