Midnight in Death by J. D. Robb is a novella that occurs just days after the previous book in the In Death series. You never know what you are going to get with novellas. Some authors use them as essential parts of the series, while others use them for plot or character development. It appears that Ms. Robb uses them to emphasize the changes in her detective, and I am a fan. 

Let's face it. Eve Dallas is not a likable character. She is brash, awkward, stubborn, determined, single-minded, demanding, mean, and ignorant of the most basic social niceties. She is a miserable friend and a clueless wife. But she's getting better, and that's the most important thing. She recognizes that friends are important even if the idea continues to make her uncomfortable. Moreover, she's improving at showing love and affection for her friends and chosen family. 

While Midnight in Death is a stand-alone murder mystery in its own right, what it does most is explore Eve's growing humanity. It's a bit like a character summation, showing how far she has come in the past seven novels. It might not be necessary for the canon, but it proves that Eve can and will heal with the right support. For me, Midnight in Death made me want to continue to see what other changes are in store for the lieutenant.