Annika Peterson

Joan discovers an unsolved murder connected to a rare prehistoric fossil when she reviews one of Sherlock's cold cases and Sherlock's responsibilities as a sobriety sponsor cross personal boundaries.

Charlie persuades a reluctant Don to investigate the death of an engineering student whose thesis on a newly constructed building pointed to a cover-up of gigantic proportions.

Both Mac and Stella find themselves under investigation, as the police probe the outcome of Mac's last case, and Stella's DNA is connected to a suspected homicide. Meanwhile, the CSIs puzzle over the death of a man dressed as an angel.

Routine disposal of drug evidence goes horribly wrong, leaving two police officers shot dead, Speedle wounded and the CSI team under investigation by Internal Affairs.

Briscoe and Curtis (Jerry Orbach, Benjamin Bratt) investigate the poisoning of an infant in a wealthy neighbourhood.

After a neighbour is murdered, Allison's fears for her own family prompt her to install a high-tech talking burglar alarm, which she later suspects may be communicating with Marie.