Complex sentence: With his fellow POWs convinced of Price's guilt, Sefton decides to take Dunbar out of the camp himself-first because he likes the odds of escape and second for the reward he can expect from Dunbar's wealthy family.
Split into simpler sentences: With his fellow POWs convinced of Price's guilt, Sefton decides to take Dunbar out of the camp himself. First, because he likes the odds of escape, and second, for the reward he can expect from Dunbar's wealthy family.