Booth is kidnapped por the Grave Digger and the Jeffersonian team must find and save him before it's too late. Meanwhile, when evidence from the Grave Digger's case goes missing, Brennan and Hodgins are suspected of taking it.
"Booth/Brennan 'shippers must have been foaming at the mouth when Peyton showed up -- Booth tells her (without prompting!) that he and Brennan are partners, nothing more."