Dominic Purcell and Wentworth Miller, <EM>Prison Break</EM> Dominic Purcell and Wentworth Miller, Prison Break

Michael Scofield has been here before — almost. The first season of Fox's Prison Break (Mondays at 8 pm/ET, Fox) culminated in the tattooed hero's carefully planned escape from an American penitentiary, but this season, the stakes have been raised: Can Michael (played by Wentworth Miller) bust the mysterious Whistler out of Sona, the hellish Panamanian jail, along with a crew of backstabbing inmates — and rescue his nephew at the same time? And is delivering Whistler to The Company's diabolical agent Susan B. Anthony really going to save anyone?

"It is taking all my wherewithal to keep from spilling the beans," says Jodi Lyn O'Keefe, who plays Susan.

The season's 13th and (possibly) final episode, airing tonight, ratchets up the action in true Prison Break fashion — by toying mercilessly with its characters and audience. Consider: A major player meets a gruesome and definitive end, another takes a life-threatening bullet and the T-Bag everybody knows and hates makes a stunning reappearance.

And the breakout? All we'll say is Sona's population won't look the same when the closing credits roll.

Because of the then-impending writers' strike, the show's producers planned last fall to craft the 13th episode as a viable winter finale, with cliff-hangers, storylines that veer in new directions, the departure of at least one character and an open road for others. Says Dominic Purcell, who plays Michael's brother, Lincoln, "There's a resolution to certain characters, and [the episode] propels others into a longer journey."

One such journey reaches a climax when Susan takes on a worthy adversary: Michael.

"When she comes face to face with him, she deals with Michael differently than she deals with everyone else," O'Keefe says. "I think people are going to be very shocked by her relationship with Michael. She's not really had to deal with anybody where she hasn't gotten away with everything, but he's on her level." And Susan gets more than a little testy when things don't go her way.

"Michael is her equal — or more so," Purcell agrees. "Lincoln's the volatile, instinctual, explosive guy, whereas Michael is much more inclined to use intellect to get what he wants. Susan has to play different cards with the brothers."

While some plotlines get tied up, O'Keefe assures fans that Prison Break still has new roads to explore. "I know what Susan's relationship with Whistler is. Let's just say they go way back," she teases.

Of course, that assumes Susan survives the episode. And on Prison Break, time has a way of running out.

Check out full episodes and clips of Prison Break in our Online Video Guide.

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