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| Aflevering | Eerste uitzending |
|---|---|
| S04E01 - Second Skin | 24/04/2015 |
| S04E02 - The 1952 Wave | 24/04/2015 |
| S04E03 - The Freedom of Information Act | 01/05/2015 |
| S04E04 - The Space Force | 01/05/2015 |
| S04E05 - The Shoot Down Order | 08/05/2015 |
| S04E06 - Seeing Is Believing | 08/05/2015 |
| S04E07 - Inside UFOs | 15/05/2015 |
| S04E08 - Unwelcome Visitors | 22/05/2015 |
| S04E09 - Alien Journeys | 29/05/2015 |
| S04E10 - Finding Aliens | 05/06/2015 |
| S04E11 - UFO Photos | 01/08/2015 |
| S04E12 - UFOs From Earth | 01/08/2015 |
| S04E13 - Summer of Saucers | 01/08/2015 |
| S04E14 - Police Sightings | 01/08/2015 |
| S04E15 - Space Shuttle Encounters | 01/08/2015 |
| S04E16 - Mass Sightings | 01/09/2015 |
| S04E17 - Mars, the Final Frontier | 01/09/2015 |
| S04E18 - Alien Communications | 01/12/2015 |
| S04E19 - Artificial Alien Intelligence | 01/09/2015 |
| S04E20 - First Contact | 01/12/2015 |