After receiving a bizarre series of encrypted messages, a group of kids embark on an adventure with an alien who needs their help.

[last lines]
Tuck: When you're a kid you think you're invisible. You think you can't make a difference. We're not kids anymore. We know now that we can do anything. Having a friend light-years away taught us that distance is just a state of mind. If you're best friends, then you always will be... No matter where you are in the universe.
Alex: I don't really know how to say goodbye, so I'm not gonna. And um... um, you're my friend you know, and when I'm old, even when you think I've forgotten, I'm always gonna be there.
Christine Hastings: Who's this?
Alex: That's Emma.
Emma: I'm, uh, he's my boyfriend. I mean, friend who's a boy.
Tuck: Awkward.
[first lines]
Tuck: All right, mom, I'm leaving. Spending the night at Alex's house so we can play a new video game.
Theresa Simms: [busy talking] Have whatever you want, honey.
Tuck: You know what, I lied, actually. We're gonna ride our bikes out into the desert, at night, alone. Without supervision.
Theresa Simms: [still busy talking] Okay, see you then, sweetie.
Tuck: Also rob a bank. Go to Mexico. Maybe even start a new life.
[leaves]
Tuck: You know, they say the girls you argue with are the ones you like.
Alex: Don't go there, bro.
Tuck: [rumbling, then a sustained high-pitch tone] What was that?
Munch: F-sharp?
Tuck: So let me get this right. So you're building a spaceship...
Alex: He's building a spaceship.
Tuck: ...and you need our help building the spaceship?
Alien Object: [yes]
Alex: This guy is building a spaceship.
Tuck: Hold up, hold up, hold up. Let me make sure I don't have any plans.
[ponders]
Tuck: Nope! We're building a spaceship!
Tuck: I've never gone a day without seeing my friends They're, like, the only people in the world who get me.
Tuck: You know what, I lied actually.We're gonna ride our bikes in to the desert at night alone.
Dr. Lawrence Madsen: Who-who are you?
Emma: Who am I? Who am I?
[dramatic sobbing]
Emma: Exactly! it's like I don't even know any more!