Complex sentence: When Czeslav, Tomasz's brother, returns home from Warsaw, hopes for Tomasz's return are high but after a month of the three living together, Czeslav has come to believe that Tomasz must be dead, a belief that Hannah refuses to accept.
Split into simpler sentences: When Czeslav, Tomasz's brother, returns home from Warsaw, hopes for Tomasz's return are high. However, after a month of the three living together, Czeslav has come to believe that Tomasz must be dead, a belief that Hannah refuses to accept.