Basic Trope: A character or an object is taken away at the end of the story for a purpose, leaving it ambiguous on what's going to happen next.
- Straight: In Bob vs. the Aliens, Bob and his squad are tasked to kill a bunch of evil alien monsters with tentacles inside a cave. By the end of the story, all the aliens have been eradicated, but Bob is the only Sole Survivor. But after he leaves the cave, the story ends when a tentacle emerges from the cave and grabs Bob and pulls him back into the cave, leaving his fate unknown. In the sequel, Alice vs. the Aliens, Alice and her crew are tasked to kill the surviving aliens in the cave and rescue Bob after learning he somehow survived.
- Exaggerated: The true final alien of Bob vs. the Aliens is a Kaiju and not only does it take Bob, but it also drags down a nearby town with people in it down further in the cave. In Alice vs. the Aliens, Alice and her crew are tasked to kill the Kaiju alien and any other surviving aliens in the cave and rescue Bob and the townspeople after learning they somehow survived.
- Downplayed: The last line of dialogue in Bob vs. the Aliens is Bob saying, "Over and out," to Alice over the tiny radio his alien captors didn't take from him.
- Justified:
- It's unknown if the story will be getting a sequel so the ending is left open in the event it does.
- A sequel is planned, but it's unknown if Bob will be used in the sequel, so his fate is left open until they decide what to do with him.
- Inverted:
- Bob is taken by the aliens at the beginning and the rest of the story is about the events that led to Bob being taken.
- Bob is taken by the aliens at the beginning and it's revealed he's a Decoy Protagonist and the real protagonist is his son, Bob Jr., and Bob's fate is left ambiguous until the sequel.
- Subverted:
- The alien pulls Bob back into the cave and then it cuts to credits. But the mid-credit scene reveals Bob kills the last alien and he emerges from the cave victorious.
- The alien pulls Bob back into the cave and then it cuts to credits. But the mid-credit scene reveals Bob tried to fight back, but the alien successfully eats him alive, making his fate clear to the audience.
- Double Subverted:
- A post-credit scene reveals a mysterious scientist entering the cave when Bob isn't looking after killing the final alien and finds the last alien egg and takes it for an unknown purpose. In the sequel, Bob vs. the Aliens 2, Bob and a new crew are tasked to kill the same aliens again, but at a science facility.
- A post-credit scene reveals a mysterious scientist entering the cave and kills the last alien and takes the last alien egg for an unknown purpose. In the sequel, Alice vs. the Aliens, Alice and her crew are tasked to kill the same aliens again, but at a science facility.
- Parodied: Even though Bob defeats the alien leader in Bob vs. the Aliens, he then goes with him willingly because, as he puts it: "Hey, we've gotta save something for the sequel."
- Zig-Zagged: ???
- Averted: The alien pulls Bob back into the cave and eats him alive, making his fate clear to the audience, and there's no sequel to the story.
- Enforced: ???
- Lampshaded: ???
- Invoked: ???
- Exploited: ???
- Defied: Bob quickly kills the last alien before it grabs him. To ensure all the aliens are dead, Bob goes back in the cave to find any surviving aliens, sees there's one alien egg left, and destroys it and kills the mysterious scientist who was planning to take the last egg after Bob leaves the cave.
- Discussed: ???
- Conversed: ???
- Implied: After Bob emerges from the cave, a tentacle also emerges from the cave behind Bob, but the ending Smash to Black before we see the outcome.
- Deconstructed: ???
- Reconstructed: ???
