A Soviet satellite has crashed into the sea and its nuclear reactor must be disarmed before it causes a disaster. Two Soviet scientists come aboard Seaview to carry out the work -- but one of them is an imposter.
| Name | Type | Role | |
|---|---|---|---|
| Berne Giler | Writer | ||
| Michael Ansara | Guest Star | ||
| Robert Carson | Guest Star | ||
| Paul Carr | Guest Star | ||
| Everett Sloane | Guest Star | ||
| Ford Rainey | Guest Star | ||
| James Doohan | Guest Star | ||
| John Banner | Guest Star | ||
| John Brahm | Director |