The essential episodes of Invasion

Watch these 15 in order and you've got Invasion — each pick states its reason.

1. 01

   S01E01 · Pilot · September 21, 2005 · 1h

   Pilot6.6

   In the series pilot, aliens surface in Florida after a hurricane and assume human form, alerting the suspicions of an Everglades Park ranger, whose ex-wife is behaving strangely.

2. 02

   S01E03 · Top rated · October 5, 2005 · 1h

   Watershed6.5

   An underwater attack on Jesse involves an orange light; and an unexplained Air Force presence smacks of a cover-up to Larkin, who feuds with Underlay.

3. 03

   S01E04 · Top rated · October 12, 2005 · 1h

   Alpha Male6.3

   A deadly virus surfaces that may be tied to runaway baboons, hunted by Russell and Underlay in the Everglades. Still, an alien presence is palpable and manifests itself in mysterious ways, including another appearance by that ominous orange glow.

4. 04

   S01E06 · Top rated · October 26, 2005 · 1h

   The Hunt6.3

   Mysteries drive Russell to fish for a luminescent being in the hope of catching an alien. Elsewhere, Derek loses interest in Kira and sets his sights on Mariel.

5. 05

   S01E07 · Top rated · November 9, 2005 · 1h

   Fish Story6.3

   An SUV spill imperils Larkin, who's lost in the Glades. Seriously injured and fearing for her unborn child, she must depend on the kindness of a mysterious stranger, who gives her a lift. Meanwhile, a desperate search is launched by a fretful Russell, who's accompanied by Dave.

6. 06

   S01E08 · Top rated · November 16, 2005 · 1h

   The Cradle6.3

   Dave identifies the skeleton found at the site of the plane crash; Larkin continues to look into the circumstances surrounding her accident.

7. 07

   S01E09 · Top rated · November 23, 2005 · 1h

   The Dredge6.3

   People who went missing during the hurricane form a support group that meets at the church, and Dave looks for evidence that they are somehow different than they were before. Meanwhile, Russell investigates toxic zones in the Everglades, where everything died after the storm.

8. 08

   S01E10 · Top rated · November 30, 2005 · 1h

   Origin of Species6.3

   Dave is abducted after he posts on the Internet that a piece of an alien life-form was found inside a dead alligator. Russell finds Dave's tape recorder with the notes for his last blog and heads out to find him, but not before sending Larkin and the kids to a motel 20 miles away.

9. 09

   S01E11 · Top rated · January 11, 2006 · 1h

   Us or Them6.3

   Russell confronts Mariel about how the hurricane has changed her; Underlay invites Dep. Sirk into his home to recuperate; and Jesse meets a lovely but odd girl while on vacation with Larkin and Rose.

10. 10

    S01E13 · Top rated · January 25, 2006 · 1h

    Redemption6.3

    Sheriff Underlay is shot three times in an episode that flashes back and forth between 1996, in the aftermath of the plane crash, and the present, in the wake of the shooting. Elsewhere, Larkin threatens to announce that the sheriff and his wife are "hybrids," much to Russell's chagrin.

11. 11

    S01E15 · Top rated · February 15, 2006 · 1h

    The Nest6.3

    Kira Underlay decides she wants to "join the new club" by going into the water. Her dad tries to stop her, but the sheriff can't keep her from spending time with some dangerous companions. Russell runs some tests on Mariel, giving them new information about being a "hybrid."

12. 12

    S01E16 · Top rated · March 8, 2006 · 1h

    The Fittest6.5

    Underlay and Russell go after Christina and Derek for attacking Russell's friend Mona. And Christina, who is a couple of weeks pregnant, is showing as if it were five months.

13. 13

    S01E17 · Top rated · March 15, 2006 · 1h

    The Key6.3

    The hunt is on for a pregnant Christina, with Russell, Szura and Underlay all looking for her. And Russell also wants to find Szura, who he believes killed Healy.

14. 14

    S01E18 · Top rated · April 19, 2006 · 1h

    Re-Evolution6.3

    Russell and Dave investigate what's happening on Szura's island in the Keys; tensions rise at school between students who were changed by the hurricane and those who weren't; and Underlay tries to find out the extent of the military's involvement in post-hurricane changes.

15. 15

    S01E22 · Series finale · May 17, 2006 · 1h

    The Last Wave Goodbye6.3

    Szura's hybrids continue to implement his master plan during the hurricane, but evacuees Dave, Larkin, Jesse and Rose encounter problems with some humans, too. Meanwhile, Underlay and Russell work to thwart Szura's scheme.