JAAN KROSS, PERHAPS Estonia’s most famous contemporary author. has been writin”g novels that confront the troubled history of his country for more than three decades. During the years of Soviet rule, his books were by necessity written to outwit censorship, concealing their criticism of the state in layers of ambiguity and irony. This is no longer necessary, but Kross, who spent eight years in a hard-labour camp, has to some extent retained the habit in Treadin’,g Air., a novel from 1998 that is the fourth of his works to be translated into English. Just as in The Czar’s Madman, the book that introduced Kross to an English-speaking audience in 1992, he leaves it to the reader to piece together the full indictment of Estonia’s occupiers – and, indeed, the full story of the central character, Ullo Paerand.