When Fringe returns for its fifth and final season, the old Fringe Division will have to band together to take down the Observers, who enslaved humanity back in 2016. Check out photos from the premiere, "Transilience Thought Unifier Model-11," which airs Friday, Sept. 28 at 9/8c on Fox.

The Fringe team will have to go on the hunt for the MIA Olivia, who did not appear in last season's flash to the future. But don't expect the family reunion to be a joyous one. "It takes on a slightly different flavor than I think you would anticipate," Joshua Jackson says of the reunion. "It happens quite quickly off the top of the season, and it's as emotional as you would imagine."

Even Walter joins in on the hunt for Olivia, but that will be very difficult for him. "He's not a whole man," John Noble says. "He's damaged to some degree and will be further damaged, and he needs to find a way to go back and gather everything he knows to reclaim his memory to use that to resolve the issue that we have with this common enemy. We are going to be damaged in the process. It's a war, so all of us will be damaged getting there."

The Fringe team will be faced with trying to track down Olivia while hiding from their most formidable foes yet: The Observers. "It's a really scary world for them out there," Jasika Nicole says. "This is the first time there's a small number of good guys and a whole world of bad guys instead of the other way around, so they have to be secret, they have to go around in disguises and not be seen by the Observers because the Observers know who they are."

In order to find Olivia, the Bishop family will need to band together, much like they've done throughout the series. "We've always said the show is this great family drama that is masquerading as this science fiction show," executive producer J.H. Wyman says. "For me, [Season 5] is a metaphor for how difficult it is to have a family in this day in age."

Tracking down Olivia means reuniting mother and daughter, which may be a bigger shock than waking up after 20 years in amber. "It's like, 'Bam! Here's your 25-year-old kid,'" Anna Torv says with a laugh. "I would love it if they just met and got on and had this awesomely close, great, loving relationship, but I have a feeling that they'll have issues to work through. It'll be interesting because we spent four years looking at this father-son dynamic, to then have a look at these two women working through the same kind of stuff."

Once Olivia is recovered, it'll be time to face being a mother, something she was hesitant about in the Season 4 finale. "Probably in her mind it's, 'How can you bring in a baby when your two parents are prepared to go out and die for their job every day?'" Torv says.

Now that the Fringe team is fully reunited, it's time to take down the Observers. Will they be successful? Find out when the Fox series bows its final season on Friday, Sept. 28 at 9/8c.