The Unblinking Eye (S04E21)

A group of four twenty-somethings, Mike (Jeffrey Hephner), Ed (Pablo Schreiber), Dana (Jicky Schnee) and Julie (Joanie Ellen), who appear to have everything, are in Queens looking for Chinese food, when they run into Kelly Watts (Kat Foster), Mike's former girlfriend. Ed talks to her, and Dana (who is Mike's current girlfriend) is a little concerned. Later that night, Mike is getting ready to propose to Dana, in front of a baby clothes store, but all of a sudden, she's shot (as is Mike). They had been at a bar earlier and some punks who were there are the prime suspects, especially since one of them had stolen Dana's purse and the ring. But the suspicion shifts to Kelly, who has a hobby of "geocaching" (going to parks and doing a treasure hunt). Police find the murder weapon buried close to where she had recently logged in and swapped treasures. Add on the stalking element, which Mike corroborates, and Kelly is now the prime suspect. (iTunes)