Meanwhile, Nicky's carrying on about crop circles in Catherine's general vicinity, then clues us in to the relevant portion of the monologue with: "In 1985, farmers near one U.S. military base suspected the source of a recent incident to be the downwash from a helicopter's rotor blades. The spinning of the blades caused the chopper to rise, forcing the air downward, in effect bending the grass below." Catherine quips, "For every action, there's an equal and opposite reaction." Words to live by, missy. Nicky explains, "Since I'm a skeptic when it comes to aliens and earth energies, I went with the chopper." And provided us with the sweet, sweet reason to see Archie.
Catherine seems as happy to see him as I am. He quickly proves himself useful above and beyond a purely aesthetic capacity -- not that his tremendous contribution in that regard should be underrated -- by analyzing radar feeds and proving that yes, a chopper was hovering above the ground the previous afternoon.
Cut to tired-seeming lab tech Henry bumping around his lab. Sara comes over, saying she got his page, then interrupting herself to ask, "Don't you work days?" "Ecklie keeps moving me around," Henry tells her dryly. That, or his shift receded into the mists, not to be seen again for another 100 years. We quickly establish that Trip and Paula were intoxicated. Drunk college kids having sex? What are the odds? Henry soon tells Sara, "You want a surprise? Check this out. I know you and Liam tested the scene for carbon monoxide, but did you check for carbon dioxide?" Sara says she didn't, explaining, "I've been a CSI for eight years. I've never processed a CO2 scene. I mean, you'd need a ton of that gas to cause serious damage --" "It's a first for me too," Henry says. He's all geeked up about it, though. Henry continues, "I found traces of blood in Trip's vomit. CO2 levels are usually .03\% of blood. His levels were 8\%." Sara explains why this is bad: "CO2 replaces oxygen on hemoglobin molecules. At 8\%, those kids would have literally suffocated on the cellular level." Henry points out, "Still doesn't explain why they were pretty in pink. Carbon dioxide, unlike carbon monoxide, doesn't affect skin coloration."