S1, E17: While on vacation in the desert, Angela contacts Brennan to ask for her help in identifying a skull - she's afraid it's her boyfriend, Kirk, who left on a photo shoot and has been missing for several days. The skull is sent to the lab, where Zack and Hodgins confirm that the victim died of a gunshot wound, had traces of peyote in his hair, and, sadly, is Kirk. Booth thinks the murder is drug-related, but the investigation leads them to a counterfeiting ring in the middle of the desert.