From "Plato's Stepchildren"
28 minutes into the episode:
SPOCK: Then you must release it, gentlemen, as I must master mine. I might have seriously injured you, Captain, even killed you. They have evoked such great hatred in me, I cannot allow it to go further. I must master it. I must control. [Cue starts]
(Spock breaks chalice with one hand.)
MCCOY: Jim. [Cue ends] This is senseless.
*Here the preceding music is exactly the same as in Spock's Brain - the entire sequence seems the same. The music fades more abruptly than it does in Requiem where it seems to end naturally.