In a story this long, not all endings can be happy. 

That’s the takeaway from the grim and almost macabre first half of the final season of Netflix royal drama “The Crown” (Part 1 now streaming, ★★½ out of four).

Ostensibly, “The Crown” tells the story of the reign of Queen Elizabeth II (Imelda Staunton, but previously Olivia Colman and Claire Foy), but for the past few seasons Elizabeth’s descendants have taken center stage, as they did in the public eye.

Now the timeline of “The Crown” reaches the late 1990s, and we’re confronted with reliving the loss of Princess Diana (Elizabeth Debicki), who died at 36 in a Paris car accident on August 31, 1997. It's a dark subject, and the series is more than appropriately glum to match funeral black. It is morbid in its dissection and depiction of Diana's death, at times gratuitous in detail and at others achingly dull and slow. It will keep you watching, if only because it recreates so much of the spectacle that really suffused Diana's life and death.

Split into two parts, Season 6 of “The Crown” first portrays Diana’s final weeks in four episodes and then returns on Dec. 14 with six final installments depicting royal events of the early 2000s. These first episodes begin with Diana and Charles (Dominic West) divorced and trying to coexist in their new reality. Diana has their sons William (Rufus Kampa) and Harry (Fflyn Edwards) and escapes England to avoid the party Charles is throwing for Camilla Parker-Bowles (Olivia Williams), whom he can now pursue publicly. Diana relies on the largesse of Harrods owner Mohamed Al Fayed (Salim Daw) for her getaway, and Mohamed in turn thrusts his son Dodi (Khalid Abdalla) on the princess, hoping a romance will bloom that will legitimize his family.

As royal devotees will know, sparks developed between Diana and Dodi, and the media circus that surrounded their brief courtship ultimately led to their deaths in a car collision in a Paris tunnel as the paparazzi chased them. "The Crown" chronicles this with devoted precision, and includes some potentially eyebrow-raising narrative additions for dramatic purposes. Then it moves to the dramatic impact of Diana's death upon the monarchy, a story that series creator Peter Morgan has already told in his 2006 film "The Queen," which won Helen Mirren an Oscar for her role as Elizabeth.

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There is little room for levity in such a fastidious account of the end of someone's life, especially someone whose life was cut short so early and unjustly. Tragedy is embedded in every scene, like the elegiac minor chords that permeate the score even when Debicki's Diana is playing soccer or sunbathing. It sometimes makes the series unbearably morose: These scenes feel almost unwatchable, not because they are poorly acted, written, or directed but because there is real human suffering behind each frame. This is true of most historical dramas, but 1997 wasn't that long ago; it still feels fresh. If Season 5 was a bit boring and uneventful, Season 6 attempts to give every moment the taut tension of a violin string. Sometimes it makes for powerful television, but at other times it's exhausting, particularly in the third episode, which chronicles the night Diana and Dodi died.

The Season 5 cast returns with more slightly overwritten speeches and quivering upper lips, and they're all passable and fine, but it's Debicki's show, and everyone else is just along for the ride. The actress rises to the occasion, imbuing her version of the People's Princess with a slightly airy naïveté, but always splendidly grounding her emotional scenes.

There is not much to say about the Queen herself, even in the post-Diana-death episode, which focuses far more on Charles (in a hyper-flattering way to the new King) and his sons than on the Windsor matriarch. Perhaps that's because "The Queen" already exists as a film, but there's no guarantee every "Crown" watcher has also seen it. It's a mistake for Morgan to ignore the supposed lead of the series in this way.

"The Crown" has won 21 Emmys and employed more British actors than a royal theater. It seems destined for an unsatisfying conclusion in next month's final episodes, considering it will end about two decades before Elizabeth II's reign did upon her death last year. But putting all that history into one coherent TV show was perhaps a futile goal. The series is too small to contain the whole story. Even with three casts and more gilded parlors than you can count, for every event it covers, three more are left out. The show had to change over the many years it depicts, but it's changed so much as to be unrecognizable. It's hard to connect the vibrant, magnetic early seasons, with Foy and Matt Smith spitting venom at each other in the poshest of accents, with what the show has become since.

And how to end all that, without really telling the end of the story? Morgan knows, and we will too, come December. But it may yet leave us unsatisfied.