Electra: blood vengeance, an old curse, an unbroken chain of slaughter

At the consummation of the plot in Sophocles Electra (lines 1417-21) we have a grim picture of an ancient pagan worldview. Clytemnestra is dead or dying,  Electra wants Aegisthus to be next in line, the Chorus responds:

Sophocles Electra 1417-21
{ΧΟ.} Τελοῦσ' ἀραί· ζῶσιν οἱ γᾶς ὑπαὶ κείμενοι·
παλίρρυτον γὰρ αἷμ' ὑπεξαιροῦσι τῶν
κτανόντων οἱ πάλαι θανόντες.

The curse is complete. Τελοῦσ' ἀραί
The dead,
laid out under earth are alive:  ζῶσιν … κείμενοι
Those long dead
are draining the blood of retribution.  παλίρρυτον … θανόντες.

Sounds contemporary doesn’t it? We have the undead, sucking blood out of the living from their dwelling place below, under the earth. We have a chain of bloodshed; death to avenge death. We have an old curse being fulfilled. Not sure what curse is in view here. Clytemnestra took revenge on Agamemnon, if you accept her story, because Agamemnon sacrificed his daughter Iphigenia to appease Artemis so he could have favorable winds for launching an armada against Troy where his armies will spend ten years dying to conquer Troy only to be wasted away on their homeward journey. Electra and Orestes are avenging the murder of their father Agamemnon by murdering their mother Clytemnestra and her consort, Aegisthus.  The curse is behind all of this somewhere. There was a curse against the house of Atreus which may be the curse in view here. Atreus taking revenge on Thyestes for stealing his bride hacked up Thyestes' children and served them to him in a stew which became the the grounds for a curse against the house of Atreus.


Postscript: Such a lovely plot. Sounds so much like Hollywood.