Guild Hall will present The Met: Live in HD’s simulcast of Richard Strauss’s one-act opera “Elektra” on Saturday at 1 p.m. First performed in Dresden in 1909, the opera focuses on Elektra, the character from Greek mythology who seeks revenge for the murder of her father, Agamemnon, at the hands of her mother, Clytemnestra, and her stepfather, Aegisthus.