The planet called Dendra seemed too good to be true. One vast forest world, marvelous climate, few dangerous beasts, a balanced hospitable ecology - all should have spelled out a good place for a human colony.

But the original survey team had registered doubts, listed it as borderline without further explanation. Nevertheless the politicians had okayed it and a colony had been landed there... and a hundred and fifty Earthly years had passed without anyone hearing from it.

Now the recontact vessel "Daedalus" was coming to check up - and they found the climate as marvelous as before, the forest green and friendly, and the colony an inexplicable disaster. There was a biological and psychological puzzle that had to be solved for the sake of all human worlds - and for the crew of the "Daedalus" it was either crack it or crack up.