Complex sentence: "Harry" collects Diego from the hospital and looks after him to avoid worrying his mother, and thus the main storyline is told in flashback as "Harry" narrates a tragic tale of fate, jealousy, abuse of power, betrayal and guilt.
Split into simpler sentences: Harry collects Diego from the hospital and looks after him to avoid worrying his mother. Part of the main storyline is told in flashback as "Harry" narrates a tragic tale of fate, jealousy, abuse of power, betrayal and guilt.