The "old Patagonian Express" was the last train Paul Theroux took in his journey from Boston to Patagonia. Some of the trains were superb, but most were deplorable and the journey was one of contrasts in people, in temperature, in scenery, in altitude, and in attitude. The people, extraordinary, eccentric, replusive, individualistic: the appalling Mr Thornberry, the bogus priest in Cali, and - very different - their blind writer Borges in Buenos Aires.