This story contains MAJOR SPOILERS for the "Stargate: Atlantis" episode "Adrift."

The toughest sell for a series is the first episode of a new season, or sometimes even the first episode of a series. That's why I'm not always a fan of using the pilot as a first episode, unless absolutely necessary, because there are very few pilots that work.

Of course, there are some exceptions to that rule, like "Battlestar Galactica," "Firefly," "Lost," and yes, "Stargate: Atlantis."

Episodes throughout the season of "Atlantis" may be hit or miss in many cases, but one thing these guys know how to do is start and end a half season, and that continues to be proven with the fourth season premiere with "Adrift."

So to catch everyone up ... the Replicators attack Atlantis after Atlantis attacks them in the third season finale. The Replicators get pissed, and sent some super stargate in orbit of the planet that blasts into the city, but the shield is protecting it. Everyone hopes the gate will shut down after a while like it's supposed to, but the Replicators are way too smart for that. When they realize that the Replicators can keep this up forever, they Atlantis crew decides to sink the city. That doesn't work, so they launch the city, and start to head for a new planet, except for one bad thing: The beam hits the city temporarily, and people (like Torri Higginson's Elizabeth Weir) get seriously hurt.

Even worse, the city comes out of hyperspace far too soon, and they are stuck, floating.

Minutes later, everyone is scrambling to try and get the city back on the road again in hyperspace before they lose the shield and die. Weir is fighting for her life. Rodney McKay (David Hewlett) is fighting for his sanity. And Dr. Keller (Jewel Staite) has her hands full.

In the meantime, Samantha Carter (Amanda Tapping) is helping to find Atlantis, which inevitably brings her to Atlantis (or should, if you believe spoiler reports).

McKay and Keller realize that Weir is going to die, so they decide to activate the Replicator nanites that are in her, to the very strong displeasure of John Sheppard (Joe Flanigan), but Weir is better, and she is ready to go on a very important mission in Replicator territory that could make the difference between life and death.

What Worked

The special effects, baby. Wow! The whole scene where Radek Zelenka (David Nykl) and Sheppard had to jump from one tower to another ... the 360-degree special effect was just absolutely stunning.

I also liked how the writers used the fact that many fans knew Weir was a goner to really put her character in peril, to make us all wonder if they really could kill her off. They didn't, but they did a great job selling it.

What Didn't Work

Why is it always up to McKay and Zelenka to save the day? I like these two characters, especially their interaction ... but they are starting to become the Wesley Crushers of this show.

I hope that now Tapping is on the show, some of the "save the day" wealth is shared a little bit so we don't always have to keep looking to the same people every single episode to step up as the hero.

Giving Credit Where Credit Is Due

"Adrift" was written by Martin Gero and directed by Martin Wood. It stars Joe Flanigan, Amanda Tapping, Rachel Luttrell, Jason Momoa and David Hewlett.

"Stargate: Atlantis" airs Fridays at 10 p.m. ET on SciFi Channel.

Michael Hinman is the founder and site coordinator of Airlock Alpha. He can be reached at mhinman@airlockalpha.com.