Walt's Island visitations are alluded to in episode 10, but that's it for explaining the mysteries of Walt for the rest of season four.

Hale Kuhina was transformed into the Santa Rosa Mental Institute, once again. A sign with the institute's name was set up on the back lawn, within view of the Hawaii State Hospital building that previously appeared in a Hurley and Charlie scene. A clean-shaven Matthew Fox was on the set. Jack’s Ford Bronco (that so far only has been seen in flashforwards) was parked nearby. A man dressed as a doctor and a couple of burly orderlies were also sighted.

A shooting took place inside HPU’s Frear Center on the second floor of 1132 Bishop Street. The scene was set inside St. Sebastian Neurology Clinic, bustling with doctors and nurses in scrubs and white smocks. Matthew Fox was there, of course. But so was John Terry. One scene took place at the hospital’s front desk, and another inside Dr. Jack Shephard’s office.

As a consequence of the big war Jack looks a little, er, messy by episode 10.

This episode will be a flash-forward installment for Jack. "We're starting to close the loop on the end of last season. Jack in the future is a man marked by weakness, but the Jack of the present is strong. You're going to understand how he made that transition."

    *  When Jack's health is seriously compromised, Kate and Juliet must learn to work together in order to save him
    * Something goes wrong as Sawyer, Claire, Aaron and Miles continue their trek away from Locke’s camp and back to the beach.
    * Guest starring are Ken Leung as Miles, Jeremy Davies as Daniel Faraday, Rebecca Mader as Charlotte, Jeff Fahey as Frank Lapidus, Sam Anderson as Bernard, L. Scott Caldwell as Rose and Kevin Durand as Keamy.

Jacket will be revisited in episode 10

    *  Jack collapses, unconscious, on the beach. Expect Juliet to take charge and perform emergency surgery.
    * Sawyer, Miles and a banged-up Claire, holding baby Aaron, make a ghastly discovery in the jungle: one dead body and an extra dismembered arm. Surprisingly, the con man turns all Big Brother on the single mum.

Jack's making another unsettling visit to Hurley in the psych ward.

Anticipate more revelations about Juliet's increasingly affectionate relationship with Jack