It starts when ALF receives a message from two surviving Melmacians, letting him know that they are going to colonize a new planet and want him to join them. ALF is torn between the continued survival of his species and his new family. Finally, he decides to join his own kind. The Tanners throw him a farewell party, have a very emotional goodbye and drive him to the outskirts of town to meet his friends' ship.
Then, just as the spaceship is preparing to pick him up, the Alien Task Force shows up, surrounding ALF. Frightened and low on fuel, his Melmacian buddies fly off, the agents close in on ALF and the credits roll, leaving viewers to assume the adorable, wise-cracking ALF is hauled off to be burned, frozen, poisoned, stabbed and finally gutted off-camera.
"That's odd. There's just a hand in here."
What were the producers thinking? Well, it would be awesome if this ending had been their plan all along and the previous 100 episodes were purely setup, an elaborate prank played by some people who really, really hated children. But the reality is the episode wasn't supposed to be the finale, it was to be a cliffhanger and the show just got cancelled before they could resolve it. Not that all of the eight-year-olds who subsequently cried themselves to sleep knew that.
Eventually, six years later, ABC aired Project ALF, a TV movie that explained ALF hadn't been executed yet, but was scheduled to be. Though he does escape the lab, he never meets back up with his Melmacian friends or reunites with the Tanners. Actually, he doesn't even seem to remember them (for some unexplained reason, they've moved to Iceland). In fact, one Amazon.com reviewer claims Project ALF made his children cry! So instead of a graphic, Muppet death, ALF is sent off into an existential collapse. Enjoy your adolescence, kids!