Light deprivation's already got the department on edge, when two crisis calls come into the station at once.  Jake Hines uses all the department's resources and gets help from his girlfriend Trudy and the other scientists at the state crime lab, but in the end, he has to climb a tall building and put himself in harm's way to catch some reckless killers.

From Six Pound Walleye :

"I got nothing but grief around here yesterday," the chief said Tuesday morning.  "What the hell's making everybody so grouchy, I wonder?"

"It's just February," I said.  "They're all suffering from light deprivation."

"Light deprivation?"  He sat back abruptly, punishing the springs in his big swivel chair.  "Who thought up that excuse?"

"It's not an excuse, it's a syndrome.  Doctors have an acronym for it now -- SAD."

"Are you serious? SAD?"

"Yeah, it stands for, uh, seasonal affective disorder. It's caused by this soupy overcast we get in Minnesota in the winter.  Vince Greeley said the other day, 'I don't think I've seen sunshine since the dog was a pup.'"

"Light deprivation.  I'll be goddamned.  What a useful discovery!"  He slammed a drawer shut, and the windows shook.  "I wonder how I should enter it in the log?"  He manhandled a lot of loose reports into a stack and smacked his big glass paperweight on top of the pile.  "Lessee, I guess I'll say, 'The support staff threw a shit fit when asked to straighten up the supply room, so Chief McCafferty, shrewdly identifying the problem' -- he raised his left hand in a mock-effete gesture, with the massive pinkie extended -- 'identifying the problem as light deprivation, took all the money out of petty cash and sent them to the tanning salon.'"

"Hey, great idea.  Maybe I'll go too.  And take my significant other."

"What, Trudy's testy too? Your dream girl?"

"Spoiling for a fight.  This morning I asked her if she wanted to go ice fishing next weekend, and she yelled at me and threw my boots out the door."

"Threw your boots out? Right out in the snowbank?"  He grinned hugely.  "But was she yelling yes or no?"

"What's the difference, if she's that mad?"

"Quite a bit, if you really want to go ice fishing."