You know, the needs of the many and all that.

Things get a bit hot as Spock's stuck in a Volcano, and Kirk has to contemplate violating the Federation's Prime Directive in order to save his Vulcan buddy:

KIRK: If Spock were here and I were there, what would he do?

MCCOY: He'd let you die.

Oh dear. They may be dealing with molten lava, but that's pretty cold.