Henry Ian Cusick in Lost by Mario Perez/ABC
Lost has been blowing my mind all season with those crazy flash-forwards: Kate's baby is who? Sayid's working for who? But the time-tripping went into overdrive with this week's brilliant episode, concocted by Lost's A-team: Carlton Cuse and Damon Lindelof on script, Jack Bender directing. Well done, blokes. There hasn't been an off episode yet, and each one feels more amazing than the last.

If you've got complaints about time spent away from Ben, Locke, Kate, Sawyer and most of the rest of the folks left behind on the island, take them elsewhere. This episode worked beautifully as a showcase for Henry Ian Cusick as the tormented Desmond. It was almost a stand-alone episode, a Twilight Zone/X-Files-style adventure with a start, middle and killer finish. And yet it also advanced our knowledge and teased the mystery of what's happening on the "rescue" freighter, while giving us a rapturously romantic climactic reunion (on the phone, but hey) between Desmond and his impatiently waiting lady love, Penelope (he's her Odysseus).

As the 'copter taking Sayid and Desmond from island to freighter goes through turbulence - the stormy manifestation of whatever time paradox is cloaking the island - Desmond becomes unstuck in time, losing his present-day memory while being thrust back to 1996, when he was in boot camp in Scotland. Zipping repeatedly between then and a confused now on the boat, he screams, "I'm not supposed to be here!" (Welcome to Lost, brother.)

In sick-bay lockup, Desmond encounters the ship's incarcerated communications officer, George (Fisher Stevens), who's suffering from an advanced case of the same time-travel heeby-jeebies, a condition that proves fatal to an Oxford University lab rat and eventually to George. Nosebleeds are the first sign (followed by seizures and death), and once Desmond's starts to drip, his anxiety to clear up this crazy situation intensifies.

All it takes is a phone call back to the island for absent-minded Professor Farraday to diagnose Desmond as having fallen victim to one of the "side effects" of leaving the island. His cure: first send Desmond to the 1996 version of Farraday at Oxford, then contact his one "constant" (that would be Penny) who bridges these points of time. What a wild fable, so much more fun to watch than it is to try to explain.

But it all ends happily enough, by Lost standards anyway, and along the way we discover that in present time, it's Christmas Eve, and that back in 1996, Penny's dad (the ubiquitous Alan Dale, the late Bradford Meade from Ugly Betty and the late Caleb Nichol from The O.C.), spent a fortune at auction to purchase the first mate's journal of the infamous "Black Rock," the boat lost at sea - and we know where it washed up - as it sailed from Portsmouth to Siam. What's this little tidbit mean? Yet another of the myriad mysteries for the more fanatical Lost lovers to obsess over.

Final detail as the episode went to black: In Farraday's journal, he has written that should anything go wrong, Desmond is his constant. Shudders, anyone?