Further in my watching of ten gajillion cop shows with my workouts, I have noticed an alarming tendency to try to add suspense in all the wrong places. Not every season has to end with a cliffhanger. If people like your show, they will keep watching your show.
I repeat: NOT EVER SEASON HAS TO END WITH A CLIFFHANGER.
But if you do choose to end your season (chapter, whatever piece of your narrative arc) with a cliffhanger, for the love of Pete can you make it one that actually…cliffhangs? Competently?
For example: “Will this be the end for the group of people this story focuses on?” No. No it will not. Everyone knows it will not. Exactly zero cop shows ever have completely disbanded their unit after that kind of cliffhanger, and the ones that have sort of disbanded it (The Wire S1 into S2) did not make it a cliffhanger. They just said: yup, now we are shifting these characters around to do something different. “Will [only female character] perish in a watery grave?” I’m just going to guess no there. “Will [main protagonist] spend his life in jail for a murder he didn’t commit?” Also going with no.
And okay, yes, if you’re doing it right, the suspense is not whether they will get out of something but how–but in the cases above, the “how” looks pretty obvious. How will [only female character] not perish in a watery grave? Well, by swimming or by having one of the others pick her up in a boat, I’m guessing. Haven’t seen that one yet, so we’ll see. And how will [main protag] get out of jail for a murder he didn’t commit? In a cop show–except for The Wire pretty much universally invested in the system working–I’m going to guess exonerating evidence. Wheee. So could you please stop pretending that we don’t know these things?
Putting a secondary character in peril is more effective than putting a protag in peril if you have established a reason for us to be interested in the secondary character–and if we actually believe you’d carry through with it. By the time you’ve watched a season of a show (read several chapters of the book, etc.), you have some idea whether it’s the sort of show that would let a bad guy murder a 4-year-old. That kind of show has to signal its turns pretty early on, or they will put off the people who are watching it to unwind of an evening with a little light mystery. We live in a narrative-savvy age. You have to roll with it.
Also more effective: putting a protag in non-mortal peril of a kind you’d carry through with. Fiction does horrible things to series protags as long as it lets them keep protagging. “Maybe their spouse will leave them or die!” Yep, unless the spouse is seriously major in the show (El in White Collar, for example), that can happen. “Maybe they will be demoted but still able to do the stuff we thought was interesting about them!” Yep. “Maybe they will have an injury they will have to work through in implausible PT episodes!” Wait, that’s a different gripe. (LEGEND OF KORRA PT FAIL ARGH.) You can make them sad. You can make them lonely. You can make them injured. We know these things happen to protags, so we can actually worry that they will happen this time.
Tim and I had a beautiful alternate universe Criminal Minds for the season in which there was an SUV explosion and it was strongly implied one of the team members was in the SUV at the time. In the time between seasons, we lovingly detailed the adventures of Aaron Hotchner after he had recovered from his massive burns and was dealing with trying to run the BAU from a wheelchair while doing actual rehab so the scar tissue wouldn’t cripple his fine motor control and still raise his son. But we knew they would never, ever do it. The question for the beginning of that season was “how will they cheat,” not “who will be killed or maimed.” And really, “how will they cheat” is pretty much always less satisfying suspense. It’s got the viewer/reader thinking about the creator, not the characters. Not what we want.