Agamemnon is the first play of the Oresteia trilogy. The Greek king returns home to Argos after ten years of war at Troy. A watchman waits for the beacon that signals victory, and a chorus of elders recalls the costly start of the expedition. Agamemnon's wife Clytemnestra greets him with elaborate honour, but the household is troubled by old crimes and unspoken anger. The play, with the prophetess Cassandra among its characters, builds a mood of dread around ideas of justice, revenge and the price of power. It is a landmark of Greek tragedy.