When you actually sit down and think about the history of Fringe, you realise that Peter Bishop has had one extremely complicated life.  He’s died in one reality, effectively been kidnapped from another reality to live in the one he’d already died in (because this is Fringe, that part of the sentence does make sense), ceased to exist entirely, only to will himself back into the universe, AND been frozen in amber for a couple of decades.

So even though the world is currently being run by the observers, and not in a good way, he otherwise has a relatively normal life now.  He’s with his wife and daughter, has a good relationship with his (sort of) father and is working alongside all of them to try and save the world from tyrannical rule of the observers.  But by the end of this episode, he’ll have gone through yet another life changing situation, and you can’t help but feel like he must have some sort of breaking point, a point where it all becomes just too much.

But we’ll come back to that later, because there are other things to talk about first.  The episode begins, appropriately enough, with Peter out by himself.  He visits a shop containing various ‘artefacts’ from what would be the recent past in the real world (i.e. the world the viewer lives in) but are much older and rarer in Peter’s timeline.  He’s there to find a new chain to Etta’s necklace, but while he’s there an observer notices him and tries to read his mind.  Peter’s been taught to fill his head with random thoughts to throw observers off, but he starts to get confused and has to leave in a hurry.  The observer alerts nearby guards to take him, but he fights them off before narrowly avoiding a grenade explosion in the sewers.  He returns, relatively unharmed, to the laboratory, keen for Etta to teach him how to shut the observers out completely.

Meanwhile, there’s a return for Phillip Broyles (Lance Reddick) to the show, as the head observer Windmark believes there is a spy in their midst, and questions Broyles over how such a thing could happen.  It emerges that he and Etta have been in contact, with Broyles taking care of a young Etta after Olivia and Peter were frozen in amber.

Walter remembers that there is a room below the laboratory, full of equipment, chemicals and various artefacts from the team’s Fringe missions before the days of the observers.  This becomes important as the latest tape they find requires them to travel to Manhattan, which is totally under the control of the observers.  In order to create a distraction to get them into the city, they use a device previously used by David Robert Jones (which suffocates its victims by closing up their airways).  Once they have reached their destination, they find a sheet of paper with a complex physics equation that Walter doesn’t understand or recognise.

Windmark has discovered that someone known as ‘The Dove’ has placed the spy amongst the observers, and also learns about the Harvard laboratory.  The team are forced to re-amber it to conceal their presence, and meet with Broyles to further their plans.  But it’s at this point that they are converged upon by observers and their troops.  Although they manage to escape the first wave, Windmark arrives on the scene to lead a chase, and he’s able to corner Etta.  In the cold manner that the observers have, he recognises that her necklace is a symbol of love, and cruelly shoots Etta in the stomach, hoping to lure Peter, Olivia and Walter back to rescue her.

They do come back, and it’s another of those character moments that Fringe has always done so well as Etta has already decided she has to die where she is, but that she can hopefully take out some of the observers and their men with a bomb.  It’s more heartbreak for Olivia and Peter and they are forced to say goodbye to a daughter that they barely know and it’s going to be interesting to see how they both react to this loss.

Olivia has often been able to mask her true feelings in order to get the job done, but will Peter be able to do the same?  He’s been through so much, that this could be his breaking point, shutting him down when he’s needed the most.

It’s another strong episode of Fringe; Etta’s death is unexpected, but somehow feels very important in the overall story and the re-appearance of Broyles as an inside man amongst the observers gives the team an extra advantage.  This is already shaping up to be the show’s best season.