Season 4:
In the fourth season, Sydney leaves the CIA to join a powerful new Black Ops unit, APO. It's an agency that's also is stocked with many of the key men in her life - her father Jack, her ex-boyfriend Michael Vaughn, her sister Nadia, and her former work partners Dixon and Marshall.

Sydney Bristow - Operative who now works for APO, an unofficial branch of the CIA
Jack Bristow - Sydney's father whom Sydney learns had her mother killed.
Arvin Sloane - Now leader of APO, which is patterned after SD-6.
Marcus Dixon - Sydney's former partner is now part of APO
Marshall Flinkman - APO's techno-geek
Michael Vaughn - CIA agent who joins APO, goes rogue and then returns to APO
Nadia Santos - Sloane's daughter and Sydney's half-sister, who gets brought into APO.
Julian Sark - In CIA custody, he works with Sydney and Vaughn before escaping
Eric Weiss - CIA agent, who is eventually brought into APO

1. Authorized Personnel Only, Part 1
2. Authorized Personnel Only, Part 2
3. The Awful Truth
4. Ice
5. Welcome to Liberty Village
6. Nocturne
7. Detente
8. Echoes
9. A Man of His Word
10. The Index
11. The Road Home
12. The Orphan
13. Tuesday
14. Nightingale
15. Pandora
16. Another Mister Sloane
17. A Clean Conscience
18. Mirage
19. In Dreams
20. The Descent
21. Search and Rescue
22. Before the Flood

Alias Season 4 DVD Details:
- All 22 4th season episodes
- "A Chat with Jennifer Garner" - Interview in which she talks about show and the season
- "Meet Mia: Syd's Little Sister" - Featurette introducing Nadia Santos and the actress who plays her
- "Anatomy of a Scene" - Featurette on staging the Train Fight and the Chopper Escape
- "Director's Diary" - Director Jeffrey Bell discusses his approach to directing an episode
- "Guest Stars of Season 4" - Featurette on the well-known guest stars of the season
- "Marshall's World" - Behind-the-scenes Featurette with Kevin Weisman's perspective on the show
- "Agent Weiss' Spy Cam" - Featurette narrated by Greg Grunberg with humor and candid stores
- Blooper reel
- Four Audio Episode Commentaries By:
  • Creator J. J. Abrams, Producer Sarah Caplan, Director Ken Olin and Jennifer Garner on "A.P.O., Pt 1"
  • Creator J. J. Abrams, Producer Sarah Caplan, Director Ken Olin and Jennifer Garner on "A.P.O., Pt 2"
  • Writer/Director Jeffrey Bell, Producer Drew Goddard and Executive Producer Jeff Melvoin on "Ice"
  • Writer Jesse Alexander, Producer Jeff Pinkner and Director Lawrence Trilling on "Nocturne"
  • - Ten Deleted scenes:
  • Choices
  • End of an Era
  • Taking It Slow
  • Ghosts
  • Six in the Corner
  • Stood Up
  • Innocent
  • Checking on Jack
  • Off the Mountain
  • A Sister's Escape
  • Buy the Alias Season 4 DVD Now!