Complex sentence: Petra (The Doctor's Daughter) brings in the letter that her father has been waiting for, after Dr. Stockmann reading the letter he discover his suspicions were right and the water from the baths is in fact contaminated.
Split into simpler sentences: Petra (the Doctor's daughter) brings in the letter that her father has been waiting for. After Dr. Stockmann reads the letter, he discover his suspicions were right and the water from the baths is in fact contaminated.