Walter disappears when the observer comes to pick him up at the lab. Meanwhile Jones is trying to cross to another reality to meet Bell and after 2 failed tries he finds the right spot but is stopped by a device Walter created lots of years ago that Peter activates to close the hole and kill Jones at the same time.
Olivia's perception impresses Nina Sharp after she whitnesses as Dunham is able to see things that one team of hers after working for 2 years hadn't seen. That ends with Nina asking Olivia to meet her in a hotel in Manhattan. But when Sharp doesn't show up, Olivia lefts the hotel upset but while in the elevator she is transported to the other reality where she meets Bell in his Twin's Tower office.
Another shocker of the finale is to discover that Peter actually belongs to the other side and that when he died when he was 7 Walter created a machine to open a hole and pick the other Peter because he couldn't leave without him.
All in all amazing chapter and show!:)