That certainly was a bittersweet ending.
Sure, the Vanderbilt baby and Libby's daughter, Clara, were rescued on The Alienist: Angel of Darkness Season 1 Episode 7 and The Alienist: Angel of Darkness Season 1 Episode 8.
So, the case was closed, for what that was worth.
But The Alienist has never been a whodunit. It's more of a whydunit.
If the title character is essentially a psychologist, of course, he and his team are going to figure out the reasons behind a horrific crime.
Take the "villain" on The Alienist: Angel of Darkness.
Libby Hatch kidnaps babies and is murderous with a knife.
But, as Kreizler pointed out, Byrnes was unable to break her because she was already broken.
The father who loved Libby killed himself, taking away any happiness that young Libby had felt.
Her mother, Mallory, was the actual monster who psychologically gave birth to killer Libby.
Mallory liked being a high-society woman of leisure.
But when her husband died, she had no interest in being a mother or, particularly, a grandmother.
So Mallory made up an attack by Libby on herself, so she could have Libby committed and give away Clara for adoption.
Little wonder that, after Libby was released, the former high-class girl became Goo-Goo Knox's moll. She found someone to give her love.
And Goo-Goo was fiercely passionate about Libby. He could have cut and run with money in his pocket, multiple times during the series, but he remained faithful to Crazy Libby.
He even encouraged her to kidnap random babies, to replace the daughter she lost, if that's what made her happy.
Unfortunately, Goo-Goo had his own anger issues, which led to the bloody events in the finale.
After it was revealed what Mallory had put Libby through, it was hard not to view her somewhat sympathetically.
However, that doesn't mean that Libby wasn't the poster child for the phrase, "She needs help." But she was about a century too early for any effective kind of therapy.
The sad thing was that Sara appeared to have bonded with Libby, who she viewed as a kindred spirit for a time. They had both lost loving fathers to suicide, being left in the custody of cold mothers.
That was probably why Sara was able to divine Libby's movements fairly well.
But Sara developed an armor around herself, determined to make her late father proud of what she accomplished.
Libby wasn't so lucky, being discarded by her mother, then slipping through the cracks of society.
Most importantly, Libby felt love in the form of her baby Clara, only to have that ripped away from her.
So it wasn't surprising that she took out her rage on those who treated her badly, such as the matron and the cop, Doyle. (What was Doyle thinking, turning his back on her?)
Otherwise, Libby had been able to stay hidden working in normal society, until her involvement with the baby abductions was revealed by Sara and her team.
The mess that developed should be dumped in Byrnes' lap. Once he learned Libby's story, he used Clara as bait to draw Libby out of hiding.
Byrnes' ploy indirectly resulted in Doyle's death. Doyle had made the mistake of serving as Byrnes' errand boy.
And once Libby had gained sight of Clara again, watch out! Sara, who must learn to lock her doors, got a late-night visit from Libby and ended up blurting out Clara's location to save John.
That should have been the end of it, with Libby in custody, but Goo-Goo was equally determined to rescue Libby from jail.
Kreizler and Sara dodged a bullet there, but since Libby knew where to find Clara, Marcus ended up paying the ultimate price.
It was terrible to see the most likable character on the series be killed off like that, in part because Lucius, no man of action, hesitated.
Lucius was ready the next time though, gunning down Goo-Goo when he threatened his compatriots.
It almost seemed that Byrnes had a change of heart through The Alienist: Angel of Darkness Season 1.
Doyle's murder hit him hard and he decided not to be a laptop for the rich and powerful any longer.
He appeared to develop a grudging respect for Sara and her team and even stood by as backup when they made the assault on Libby's childhood home.
Could the young detective that Sara introduced in the end, Kitty Byrnes, be his daughter or granddaughter?
Sadly, circumstances conspired against John and Sara getting their happy ending.
But he's going to get the child he wanted from Violet and she can focus on her detective agency, which continues to flourish.
Still, maybe Laszlo will find happiness with Karen. She gave him just the kick in the pants he's needed to break out of his academic shell. She was a great addition to the cast.
Unfortunately, the new additions left less time for old favorites, Stevie and Cyrus, as well as newcomer Joanna, who was criminally underused then written off.
Also, Dr. Markoe never got his comeuppance for that mistress baby mill he was running, which was disappointing.
This, regrettably, promises to be the end for The Alienist. Everything was left fairly tied up. The first two seasons were based on Caleb Carr's two Alienist books. So another season would require an original screenplay.
Angel of Darkness took forever to be picked up. So, unless ratings are spectacular, it's unlikely TNT will make the effort for what looks to be an expensive production.
So let's say goodbye to Laszlo and company and hope for a pleasant surprise.
To revisit this season, watch The Alienist: Angel of Darkness online.
Were you sorry to see Marcus killed off?
Were John and Sara not meant to be?
Will Laszlo find happiness?
Dale McGarrigle is a staff writer for TV Fanatic. Follow him on Twitter.