I'm pretty sure kids from 80's and 90's will remember this version of Peter Pan.
Fox's Peter Pan & the Pirates: [link]
I was rewatching the series, for nostalgia and because I really was in love with the series (and this version of Peter Pan, which I find really interesting in terms of design), and I end up watching the two final episodes of the whole serie.
Now, I have to say, if you are interested in watching the whole series, just read a few lines to see if it interests you. If not, read the whole thing.
Until that episode, all others were child friendly, with some dark scenes, but none of them were too much. Until the two last episodes, called "Ages of Pan" (part 1 and 2).
Now, the spoiler starts.
You can see the episodes starts like all the others, with Captain Hook chasing Peter Pan, and being captured and tied to a tree (Hook). Then, in front of him, Peter has a something like a cannon, with pointed bamboo, also saying to want Hook to go away, or end up dead, and starts shooting the bamboo..
From that point I started to saw the thing was serious. Until now, Peter Pan never tried to seriously kill Hook.
But, you can see the machine is put so every bamboo goes around Hook.
While Peter is shooting bamboos at Hook, he explains him that he doesn't care about dying, since he had a full live: he was a kid, a teen and a man, and Peter will never get that, he will stay as a kid forever and never be a full man.
Peter, hearing that, decides to just go, telling the Lost Boys to do whatever they want with Hook (Hook frees himself). Back at the tree, Peter paint in his face some lines to look like an old man, and starts acting like one.
At this point, the episode is, more or less, having a balance between fun and dark (like all other), but then Peter makes his decision to grow up. He goes away and disappears for some time. Once the Lost Boys find him, you can see he's a teen, meaning he has started to grow.
Being a teen means saying no to anything childish (as every teen does), and he says to Tinkerbell he doesn't believe in her. Tinkerbell starts to fade away, leaving the Lost Boys so they don't see her, and Peter goes his way.
And now, is when the dark stuff starts. Since Peter Pan is the eternal youth, and he doesn't believe in magic, Neverland itself starts to decay. All trees and plants start to die, water starts to disappear, leaving nothing but dead floor, and Tinkerbell keeps weakening. She's found by Hook and the pirates, and she asks him if he believes in her. With the answer "Of course, you are in front of me", Tinkerbell is momentarily saved, and she manages to escape Hook and looks for Peter Pan. When she's saved by Hook, you can see Neverland returns back to almost normal, but is still decaying.
Hook find Peter, but he's all grown up, being now a man. Unable to recognize him, Hook tries to just put him away from his way, but Peter confronts him by using the words (trust me, is a very strange scene). Peter Pan just walks away and Hook decides to let him go, trying to find the young Peter to repair all the mess Neverland is now.
Peter then meets again Tinkerbell. She ask him if he believes in her, and then Peter repeats the sentence "Of course, you are in front of me", since he's a grown up man and uses logic more than a teen, but he's unable to remember her. She manages to survive, since he believes in her, but Neverland keeps dying.
And this is the moment when we can see that Neverland is dying because Peter himself is, actually, dying because of quick aging (since now he believes in her, and Neverland still goes to it's end).
Peter keeps growing until he's an old man, and meets again with Hook, who finally recognizes him. Falling down a cliff, Peter is saved by Hook only to be killed back in the ship, where all Lost Boys are captured.
Hook makes Peter jump off the ship into the sea, but when Peter jumps, he grows to a very old man, and Neverland just stops existing. Everyone is falling into a dark hole, where there's nothing but darkness.
Tinkerbell manages to go where Peter is, and the twins tell her she's the only one who can save him ( I won't explain how, since I want to leave you some mystery to solve >w<). Peter finally recognizes her, and remembers his time as a kid, and with that, and some help from Tinkerbell, goes back to his child form, and with that, Neverland is reborn.
The scene after this is a big "WTF???" For all the characters except Hook, and all the viewers (I'll leave to you to find out).
For me, even being used to dark shows, these two episodes were kind of a shock. The whole story is well written, you can actually see how everything is dying, how Peter Pan is decaying along with Neverland, how none of the characters (except Tinkerbell) know anything about what's really happening (They just think is bad weather), etc.
For a cartoon for kids, this was really dark. I've seen every character near to death, but not the whole place dying slowly and, as I can see by Tinkerbell, painfully.
I think they need to do shows and episodes like this more often XD.