Fox’s science fiction staple returns for its fourth season debut tonight, with a summer’s worth of mystery and speculation behind it.

After the cliffhanger finale to Fringe season three, will the premiere answer fans’ burning questions or keep them guessing?

Fringe opens up a week after Peter created the universal bridge in the finale. The Fringe divisions of the FBI in both the primary universe (ours) and the alternate universe (theirs) have established a sort of safe house where people and objects can move safely and easily between realities. Olivia (Anna Torv) seems to be the unofficial liaison, which causes noticeable strain on her character’s much-abused sense of trust, as her alternate is also a liaison.

Back at the Harvard lab, Walter Bishop (John Noble) and Astrid (Jasika Nicole) are productively investigating the evidence gathered in Olivia’s regular duties. Long-time Fringe fanatics will notice that they’re working on cases and problems that have already been solved. When FBI agent Lincoln Lee (Seth Gabel) catches up with Olivia, they don’t recognize each other – an observant outsider notes that recent events have repercussions both forward and backwards in time.

Walter is broken, even more so than before. He’s prone to periodic breakdowns that bring the division’s work to a screeching halt. He lives in the lab with the constant aid of the FBI. Between Walter’s tedious mental state (which is presumably unanswered for the team) and Olivia’s recurring personality flaws, the more fragile aspects of these characters – the ones that had been repaired or at least helped over the last three years – are back in full force.

To put it bluntly, everything old is new again. In a move reminiscent of Eureka‘s universal shift, the timelines of Fringe’s dual realities have both been greatly altered by the erasure of Peter Bishop (Joshua Jackson). After the events of last year’s finale, it appears that not only is Peter not present in the, uh, present, he died as a boy in both universes, or something happened to create that impression.

This creates a plethora of questions with answers seemingly a long way off. Peter is the catalyst for almost every major event in Fringe thus far. If he never existed, why did Walter cross universes in the first place? How did the two Fringe divisions come into contact? How is Walter’s psychosis being handled if Peter was originally brought on because he was the only one who could help? If Peter wasn’t there to explain the stabilized connection between universes, why aren’t both sides shoving nukes through the doors? Why was the faithful bovine Gene so cruelly and unceremoniously recast? (That one might not be relevant to every fan.)

Alas, no answers are forthcoming in the opening forty minutes of the new season. Without the generous prologue and brief appearances by the Observers, viewers wouldn’t have any contextual clues at all to the more pervasive reality. Peter is coming back, as die-hard Fringe fans know, but there’s no indication of it thus far. A quick glimpse (don’t blink!) is the only clue that all is not as it appears.

That said, there’s hope to be had for the overall arc of the season. Little touches, especially in dialogue from Anna Torv and John Noble, indicate that the writers are carefully reconstructing the story around Peter’s absence. The short appearance by the Observers gives some guarded clues to the true nature of events.

All in all, the episode is slow, largely retreading over past Fringe events because the characters haven’t actually lived through them yet. This may have seemed necessary to establish the altered timeline in fans’ minds, giving it weight and substance for the reality-bending events to come. The FBI agent played by the always-watchable Joe Flanigan (Stargate Atlantis) is quickly sacrificed for this purpose. Seth Gabel is effectively established as Peter’s stand-in on the primary Fringe Division for however long he’ll be needed.

It would have been nice to be given at least one or two clues to Fringe‘s series-spanning mysteries, and their absence is felt at least as sharply as Joshua Jackson’s. But a return to the activities that make the core characters of Olivia, Walter and Astrid so much fun to watch are much appreciated, and as long-term Fringe fans know, good things come to those who wait. The monster-of-the-week, while technically a retread, provides a welcome bit of action and room for Gabel to shine.

It’s a slow return for Fringe, but certainly not an unwelcome one. The mystery surrounding the Observer’s activities are the primary take-away. Here’s hoping that the coming weeks do more to set up the arc that will drive the season (and quite possibly the series) to its conclusion.

Fringe airs Friday nights at 9:00 PM on Fox.

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