Warrick, meanwhile, is still at the scene with Sara. As he snaps pictures of assorted parts all over the road, he stops to photograph a bolt that looks as though it's been sheared. He then picks up the bolt and walks over to Sara, asking her to check it out as well. They teleport to a lab, where they test the bolt's composition. What they see on the screen causes them to exchange a meaningful look of some sort.
In another part of the Labitrail, Nicky's telling Gil that he just got a copy of the bus's service report, and the vehicle was allegedly in perfect working order, serviced the week prior to the crash. Gil invites Nicky to look down at the undercarriage on the floor and asks, "Does this look like it's in perfect working order?" Nicky is forced to concede that it does not. Just then, Warrick and Sara come in to share the news: they've got a three-quarter-inch bolt with a hex head that says it's a grade eight. Sara explains that bolts are graded according to their hardness, and a grade eight is supposed to be stronger than steel. Gil asks if Warrick and Sara did a Rockwell Hardness test; Warrick replies, "I hit it with a true-blue. It's not a grade eight. It's a grade five." Well, someone screwed up something, then. Gil digests this news and inspects the remaining bolts, musing, "Often when there's one, there's another one." Sara wonders if the bus company was using bogus bolts. Gil notes that inferior bolts would cause the suspension to give, thus forcing the bus to veer all over the road, and hypothesizes, "If the sheared bolts were the first action..." Warrick interrupts Gil reaffirmation of Newton's Third Law by pointing out, "No, the bolt snapped halfway through the skid, after the bus hit the K-rail." Gil demands proof; Sara supplies it with, "Gouge in the road." Gil begins thinking of Plan B.
Gil: Broken rod arm, maybe?
Nicky: Okay. Driver hits the brakes, initiates the skid.
Gil: Why'd he hit the brakes?
Nicky: Another vehicle.
Sara: Nope. Only two sets of skid marks on that stretch of highway.
Warrick: Yeah, and that Camaro's skid marks place it behind the bus.
Gil: So I ask again -- why'd he hit the brakes?
Nicky: Man, there could be a million reasons.
Gil: Fortunately, we're just looking for one.
Okay -- let me just say how much I love this episode. This may well be my favorite episode of this show, and here's why: the team is working together, which I always appreciate; we get to see how they enter a crime scene and begin making sense of it; we see how they reason through the evidence and process assorted theories. It's not often that a television show manages to make deductive thinking look interesting, but this episode's really made it exciting, and managed to engage all of the viewers in the act as well.