Fringe/Recap/S02/E19

Season 2, Episode 19:

The Man from the Other Side
The Fringe team investigate when a pair of dead teenagers are found along with a strange organic object. Walter discovers that the object is a Shapeshifter in its original form, deformed as a result of the unstable method used to travel between universes. Two more Shapeshifters have also arrived, and after taking the forms of the teenagers they make contact with Newton and put a new plan into action that involves planting devices in specific locations around Boston. At the same time, the Fringe team discover that an errant signal from the alternate universe has also crossed over along with the Shapeshifters: from it, Brandon and the Massive Dynamic team are able to determine that within a day and a half of the Shapeshifters' arrival, the two universes will be "in sync". The Fringe team realise that when the universes are in sync, Newton will attempt to bring something over from the other side.

Walter revives the deformed Shapeshifter and before it dies, it gives the name of its target, a local doctor. Another Shapeshifter victim turns up, a bank manager, and Olivia theorises that both individuals had been targeted for their access to particular locations. Walter guesses that Newton is attempting to set up three harmonic resonance devices in a triangle that, when activated, will swap the matter in the centre of the triangle for the matter located in the same space on the other side. From the locations they have, the Fringe team identifies the most likely location, a condemned bridge where Newton is in the process of setting up the machinery that will activate the rods and begin the process.

Fringe Division arrives just as the universes come into sync and the rundown bridge begins to swap places with the intact bridge from the other side. Walter and Peter have a device that will stop the matter transfer if set up near the centre of the resonance, fearing that Newton is planning to bring over an army of soldiers or Shapeshifters, and Peter sets it up despite Walter's warnings that anything too close to the centre of the resonance during the transfer will be disintegrated. As the transfer takes place, Peter sees a man appear on the bridge and leave via the opposite end -- entering the prime universe -- before he gets the machine working. The energy of the transfer disintegrates a nearby FBI agent, but Peter is merely thrown against a car and knocked out.

The man from the other side escapes with Newton, who helps the "Secretary" to recover from the journey in a secret location. Peter wakes up in hospital a day later. He's figured out that he didn't disintegrate for the same reason that the man from the other side didn't disintegrate: they're both from the alternate universe. Walter tries to explain but Peter demands that he leave, angrily claiming that he's not Walter's son. Later, Olivia discovers that Peter has checked himself out of hospital and ditched his phone, disappearing off the FBI's radar.