Fringe - The Doomsday Device

At the 2nd season finale Walternate gave Peter's the task to built a machine that according to him can "protect" their universe from the other one and assure that they can survive the impact if there was a war coming.What Peter didn't know is that this machine called 'The Doomsday Device' is capable of massive destruction which would result the end of a universe and since Walternate is the one to use it it's no question that the prime universe is his target.Tricky thou the thing is that the machine only 'responds' to Peter's DNA.Not much after the events of 'Over There' turned out that Bolivia(or Fauxlivia or whatever her name is) was sent to the parallel side in order to recover the pieces that are missing from the device or the Wave Sink Device as it was called later.So Peter was the first piece of the  puzzle and Bolivia's mission on the other side was to manipulate him into finding and building the machine to "resolve the problem" between the two worlds.Lucky for us we got our Walter too who begins suspecting things and takes a closer look into the blueprints and the device and realises that not all things  are what they look and after succesfully seeing through Bolivia, they realise her true identity and arrest her.Ofcourse naturaly things don't go as planned and she manages to get back to her side with leaving a dead Bryoles in the other side.Olivia get's home after a long walk on the other side and the Fringe Team aquires the mysterious typewriter machine that allows them to communicate with the other side.Thing's couldn't go any better right? xD