The remains of two victims are found in a cave in a park, and after being taken back to the Jeffersonian for analysis, the female victim is identified as Hillary Fuller.
Booth and Bones discover that Hillary was a recovering alcoholic and was spending much of her time sponsoring another recovering alcoholic named Felix, a migrant worker from Guatemala.
The focus centered on people who might want them dead - her boss, his wife.
But, it turns out that back when Felix was out of control, he bought alcohol for a minor who then lost control of her car while driving and died.
Turns out this girl was the park ranger's niece, and in order to get revenge on Felix for what he had done, he sprayed him with pepper spray and pushed Hillary and him off the edge of a cliff.
Meanwhile, Clark Edison returned to the Jeffersonian from Chicago.
Angela and Hodgins continue to talk about the baby and act generally cute.
Booth's girlfriend, Hannah, has arrived from Afghanistan, having gotten a transfer to the D.C. press corp to be with him. Now we get to see jealous Brennan
It's no longer Booth pursuing Brennan; the roles have completely reversed.
Brennan admitted to fantasizing about her and Booth together while she was away, and Hannah got to her so much that she went off on Clark.
Of course, regressing to typical "Brennan in denial" fashion, she claimed it was all for professional reasons and laughed it off.