Yes, there are people who like D/L, there are people who are indifferent to D/L, and there are people who dislike D/L. There are all kinds of people, yay! Now back to the spoilers:
The next episode isn't the crossover--that episode is 3.22. The promo apparently shows footage from several upcoming episodes, including the crossover/spillover/sleepover.
Let me try to get this straight, since the final few episodes are getting jumbled up in my head
(I'm copying this from another board where the spoilers were posted by episode, so some of it is word-for-word from earlier in this thread, and some isn't.):
3.21 "Past Imperfect"--Mac, Stella and Flack work on one case. The death reminds them of the M.O. of a murderer who got off on a technicality.
Hawkes starts out with Mac and Stella, but he ends up working the other case with Danny (and Lindsay, I think), that takes them to Coney Island.
Sid and Adam are both mentioned.
3.22 "Cold Reveal"--Part of the storyline from episode 21 continues in this episode, and Mac is the subject of an investigation, and may face charges.
The case that Mac, Lindsay and Hawkes are on involves a young guy who falls to his death while bungee jumping.
Danny's case, which involves the crossover with "Cold Case," takes him to a woman who runs a foster home, and she used to know Stella.
Gerrard and the chief of detectives are in this one.
3.23 (No Title Yet)--It ties in with episodes 21 and 22 which deals with a suspcious death in episode 21 and Mac losing his gun and badge in episode 22. It's like an internal trial.
The case involves a man dying the night of his fiancee's bachelorette party. Peyton is there.
3.24 "Snow Day"--Mac, Stella and Hawkes are at the lab, dealing with a 'gas leak.' Danny and Adam are held hostage. Flack offers to trade himself for Danny and Adam. Peyton and Sid are mentioned.