According to this promo, "the season's biggest shock" is in store for Bones viewers. It will apparently go down on "The Beginning of the End," as teased here.
Brennan: I have the sense that everything's changing. Booth: Not everything. Look, we're still partners, and Taffet, she's put away. You feel good about that, right? Brennan: You almost died, Booth. That could happen again. What if next time I can't get to you? Booth: That's not going to happen again. Brennan: I envy your ability to substitute optimism for reality.
Caroline: So, how's your girlfriend holding up? Booth: She's fine...she's not my girldfriend. Caroline: Oh! So those looks between you... Booth: Nothing. Caroline: Right... hope you're more believable in the stand.