Say what you will about Dr. Jack Shephard; whatever your beef may be—and there are plenty to choose from—the man has a knack for remembering a name. The name in question is that of Desmond Hume (Henry Ian Cusick), whom Jack met only briefly on a transpacific flight. (We first saw him in Season Two as the mysterious hatch-number-enterer.) But, hey, this quite terrific episode belonged to Desmond and when you're the guest of honor, people tend to remember your name.

This episode explains so much, but it’s hard to explain what it explains. Let me explain: My girlfriend does not watch Lost (she's busy living something called "her life"), but she was curious to see an episode of the show that has kept me so preoccupied since the calendar year began. (Oh, pre-Lost Mike of 2009—your ignorance really was bliss.) She found it slower-paced than she expected and, naturally, had absolutely no idea what was going on. That's my fault, but what was I supposed to tell her? It would take longer to explain than the time she would possibly care to spend on the subject. This episode was a lot like the song "Tomorrow Never Knows" by the Beatles. Only true Beatles fans love this song because, as the last song on Revolver, it set up the more experimental music yet to come on Sgt. Pepper's Lonely Hearts Club Band and Magical Mystery Tour. To non-Beatles fan, though the song sounds like noise. "Happily Ever After," to a non-Lost fan, even more so than other episodes, was noise.

"I understand." These two words were uttered for the first time in the six-season history of Lost. O.K., that’s possibly not true, but it has to be the first time the person saying them, in this case Desmond, was 100 percent correct. That's what's exciting: he's the first character to figure this whole mess out. Strange, considering the small amount of time it took him back on the island to do so—so much for your sleuthing skils, Doctor Shephard.

Have you ever had a dream when you realize that you're in a dream and can sort of control the dream? This is what's going on with Desmond. He, too, has an entirely different life in the alternate dimension where Oceanic Flight 815 did not crash; there, he has no special someone in his life and works as a sort of consigliere for Charles Widmore, his bitter enemy (and father-in-law) in the original timeline. But thanks to an attempted drowning murder-suicide by the not dead, flash-sideways Charlie Pace (Dominic Monaghan)—honestly, if I hear Drive Shaft's "You All Everybody" one more time, I'm going to drive a car off of a bridge, too—Desmond has seen flashes of his island life, including of his wife, Penny. Desmond eventually learns how to keep his memories from both timelines intact while shifting consciousness from one timeline to the other.

How is Desmond doing this? Well, he's sort of done it before. In Season Four, as I'm sure you recall, Desmond was caught between two time periods in the same dimension; now he’s caught between two time periods in different dimensions. Nifty trick. Widmore thinks so, too, which is why he "volunteers" Desmond for some sort of electromagnet experiment that, Widmore believes, will trigger Desmond's time-traveling ability. Widmore was right.

In Season Four, Desmond, uncontrollably hopping back and forth between 2004 and 1996, seeks out help from Daniel Faraday, a leading time-travel researcher, by tracking him down in the U.K in 1996. This Season, there's good news and there's bad news. The bad news: In the main, plane-crash timeline, Faraday died in Season Five. The good news: In the alternative, non–plane crash timeline, Faraday, who is Widmore's son, still lives at home. Not only that, he's also had visions! He even knows about the nuclear bomb that altered the future and split the timeline into two dimensions. Faraday explained to Desmond that he, too, had a vision of his true love, and that, when he woke up, even though he's just a musician (and apparently a pretty bad one since he couldn't even get Drive Shaft to play with him), he sketched out his ideas for time travel... or dimension hopping... or something. Disappointingly, it looked nothing like the flux capacitor.