An arm falls out from underneath of a bus and after an investigation of the bus, the CSIs find the remains of the body stuck beneath the bus. The bus in question was carrying inmates from a women’s correctional facility, leading the CSIs to believe that an inmate tried to escape during transport. But when tests reveal that the victim was dead before the transport began, the case becomes more complex. Meanwhile, Grissom looks into a case involving a man stabbed once in his chest and four times in the back – all wounds being exactly the same height.