Mac, Aiden and Flack investigate when Elaine Curtis is found dead at a dog competition, a knitting needle sticking out of her chest, and no shortage of suspects ranging from judges to trainers to contestants. Stella and Danny investigate the death of bicycle messenger Michael Starling, but the crime scene may have been anywhere along his route.

The detectives investigate a murder at a grocery store that is also connected to the death of a young man with the tattoo "Tanglewood" on his back. A third case involves a woman who was killed in a hit-and-run auto accident.