E.J. Mackernutt, Jr., an 11-year-old boy who has always been fascinated by space and astronauts, sneaks into Cape Kennedy and becomes a stowaway on a spaceship scheduled for a lunar landing. After he is discovered, NASA at first cancels the landing, but E.J. and the astronauts convince them to go forward with it. Problems arise when one of the astronauts is incapacitated by illness and the other two are stranded on the moon's surface, but E.J. is able to command the space capsule and save the day.
| Actor | Role |
|---|---|
 Lloyd BridgesCharlie Englehardt | Charlie Englehardt |
 Jeremy SlateAstronaut Capt. Rick Lawrence | Astronaut Capt. Rick Lawrence |
 Jim McMullanAstronaut Ben Pelham | Astronaut Ben Pelham |
 Morgan PaullAstronaut Dave Anderson | Astronaut Dave Anderson |
| MMichael LinkEli 'E.J.' Mackernutt, Jr. | Eli 'E.J.' Mackernutt, Jr. |
 John CarradineJacob Avril | Jacob Avril |
| JJack CallahanDr. Jack Smathers | Dr. Jack Smathers |
 Charles ConradHimself | Himself |
 Walter BrookeWhitehead | Whitehead |
 Keene CurtisTom Estes | Tom Estes |
 Edward FaulknerEli Mackernutt, Sr. | Eli Mackernutt, Sr. |
 Jon CedarHans Hartman | Hans Hartman |
| BBarbara FaulknerMrs. Mary Mackernutt | Mrs. Mary Mackernutt |
| SStephen RogersJoey Williams | Joey Williams |