Season 4: Episode 14 - Playing with Matches

Playing with Matches: When a drowning victim spills out a self-cleaning public restroom, it first appears to be a freak accident. Unfortunately, the CSIs soon discover it was foul play. The victim was a pen-pal to a convicted felon, and using “Wila” writing, or miniaturized writing hidden on the backs of postage stamps, the two hatched a plot to spring the felon from prison. However, in a bizarre twist, their plan backfired when the victim was accidentally killed in a plot by a rival public restroom company. Meanwhile, when a flame-engulfed body comes out of nowhere and slams into the windshield of a responding FDNY fire truck, the team is hurled into the world of street-luging--an extreme sport where a thin wooden “sled” and a few inches of air are all that separate life and limb from flesh-ripping asphalt.