Up in Smoke
S6 episode 16 Aired on March 2, 2006

Excessive smoke coming from a fire place alerts the fire department, which in turns calls the CSIs as a charred body is found inside the chimney. The body is burnt beyond recognition. A gym membership card found on the body identifies him as the son of the house's owner. The opportunity to search the house leads Catherine and Warrick to look for any evidence about a one-year-old disappearance of a young girl who was on her way to this house before she vanished without a trace.