In the Big Apple, an elite group of first responders exists. The "Boys in Blue", or NYPD, is well known as being one of the best in law enforcement. On the other hand, FDNY has produced some high quality blaze battlers, including Steve Buscemi, famous for such films as Reservoir Dogs and Fargo. Yoo-hoo casting directors! Talk about a guest star...

During a race to a call, Engine 3 learns about people possibly trapped in a building. This is nothing they haven't prepared for. What they don't expect is the body which smacks up against the windshield. The impact is so great, a spider's web of damage covers most of it.

It takes no time at all for Det. Mac Taylor (Gary Sinise), head of the evidence roundup team, to be called in by Det. Jessica Angell (Emanuelle Vaugier) for help. He is wise enough not to tackle this on his own, so Det. Danny Messer (Carmine Giovinazzo) comes too. Soon, Det. Lindsay Monroe (Anna Belknap) arrives.

When an insignia patch is discovered nearby, the case takes a strange twist. The design resembles one worn by Alan Shepard on Mercury 3. Mac is quick to quote, "Houston, we have a problem."  I have to hand it to the writers to have Gary Sinise utter a sly salute to Apollo 13. The victim is wearing a suit of sorts, leading the detectives to consider the role of outer space.

Back at the lab, Dr. Sid Hammerback (Robert Joy) tells Mac his victim died of smoke inhalation when toxic fumes filled his helmet. A meat thermometer was also discovered during autopsy, which accounted for the stab wound. Since rate of impact was approximately eighty miles per hour, Sid surmises a re-entry to the earth's atmosphere has something to do with the case. When Mac just looks at him, Sid mildly says he is not a forensic expert.

Kendall Novak (Bess Wohl), an in-house lab technician, helps by suggesting a more reasonable explanation. She thinks the victim might have been street luging, which is exactly what it sounds like. Accelerant increased the rate of speed so homemade sleds on wheels flew down a hill. When Messer and Angell attend a competition, they find "Mercury" (Jason Chambers, Human Weapon). He admits to the stabbing, but claims innocence as to the death.

A luge professional, Sandra "Concrete Cowgirl" Cook (Nicole Marie Lenz), owns the suit. She wanted to help the victim take a step further in his career, since he seemed to have a talent. Eventually, she is cleared of wrongdoing. The death is determined to be accidental.