I had forgotten that Desmond was shot by Ben back in Los Angeles, but the show reminds me. Now Charles Widmore has him on the Island and is all, "The island isn't done with you yet."
Widmore's crew is working on a series of WTF experiments. I quite literally have no idea how to explain them. There's a giant coil, an electric pulse, a white rabbit, and a dude gets burned and dies. Desmond's put into the box with the giant coil next. Widmore says that Desmond is able to survive a large electromagnetic event, and so he'll be fine. Indeed, the electric pulse coil thing happens, and Desmond is all like electrified and stuff, but he survives.
Non-Island Desmond works for Charles Widmore and seems to get along great with him. Charles sends Desmond to fetch the recently-arrested Charlie, whose band is supposed to play at some Widmore event.
As they're driving, Charlie jerks the steering wheel and sends them careening into the harbor. Under the water, Charlie puts his hand up to the window and Desmond gets a déjà vu feeling - and actually sees a flash of Charlie doing the same thing with the whole "Not Penny's Boat" drowning incident on the Island.
At the hospital, Desmond is given an MRI, and sees flashes of memories that... well... didn't happen for him but happened for the Other Desmond. He sees Penny and his son and all that.
Mrs. Widmore is Eloise, and she's as strange and cryptic as ever. My man Daniel Faraday - hells yes! - is Daniel Widmore now - the offspring of Eloise and Charles. He wasn't before, right? He was just Eloise's son, at least that's the only parent we knew. Anyway, he approaches Desmond and shows him some crazy physics equations he recently wrote - only this Daniel is a musician, not a physicist. He asks Desmond, "What if this wasn't supposed to be our life? What if we had some other life and for some reason we changed things?" He must smoke a lot of weed as a musician. Desmond and Daniel discuss their weird déjà vu feelings related to their respective chicks. Daniel tells Desmond that Penny is his half-sister, and where to find her. They meet, and it's adorable, and I remember how much I love Desmond and Penny.
At that moment, we're taken back to the Island, where Desmond has survived his electromagnetic event. He has apparently had those flash-sideways as memories, and now he's all-in on helping Widmore on the Island.
As Desmond's walking through the jungle with Widmore's people, Sayid ambushes them and tells Desmond to follow him.