Climate change has brought extremes but more importantly because of environmental refugees there was a war started that engulfed the world.
Domes called Shields were placed over the cities to have safe places to live. This brought the fighting to an end in most places as the Shield Makers insisted that a place be safe and stable before they would allow the dome to be made.
Panacea was named another city but when they started over they gave it a new name. It is most like on the east coast of America but I'm tempted to place it further down in Mexico as I have made it generic enough.
Halcyon - otherwise known as Hal is a bioware genius. She suffered from cancer when younger but discovered how to hack the human genome with ancient symbols. Now she lives in an old warehouse complex looking for people to test her theories on while inventing strange and wonderful contraptions.
Misha - His father was a Russian man that helped set up the city but was betrayed by Portland and murdered. Misha trained by his father and a martial arts expert to be a bodyguard has been bouncing around aimless after his mother died.