Lady Olenna's Confession

In this suprising scene from episode 4.4 (two shows after Joffrey's death from poisoning), Lady Olenna Tyrell (Diana Rigg) confides in Margaery (Natalie Dormer) that it was she who killed Joffrey Lannister. She of course has the help of Lord Petyr Baelish as a co-conspirator. Yet Littlefinger—once a pimp, always a pimp—has his hands full with Sansa, and it is Lady Olenna who retrieves the bead with the poison from Sansa's necklace, and it is she who puts the poison from that bead in Joffrey's goblet.