When we last saw "Doctor Who" on Sci Fi earlier this year, the Doctor became a new man — literally.

"Time Lords have this little trick," the old Doctor (Christopher Eccleston) explained to his confused friend Rose (Billie Piper) in his dying moments. "It's sort of a way of cheating death. Except ... it means I'm gonna change. And ... you're not gonna see me again. Not like this. Not with this daft old face."

Then, in a flash, everything was different.

Don't worry, though — the "regeneration" from a ninth incarnation (Eccleston) to a 10th (David Tennant) is all part of the mythology of the British fantasy show.

Those who aren't familiar with the Doctor's journeys (the original series ran for 26 years on BBC television) need not feel left out. Here's what you need to know: The alien Doctor travels through time and space in his bigger-on-the-inside ship called the TARDIS, which is disguised as a blue police box (a common sight on British street-corners when the show premiered in 1963). Accompanying him is Rose Tyler, a London shop girl who showed tenacity and a gift for adventure in the new series' first season. At every turn, the two fight alien invasions and the specter of injustice using mainly their wits.

The new 14-episode season finds Rose dealing with the aftermath of the Doctor's radical change of appearance.

Tennant's version is friendlier, more confident, more manic and more apt to crack jokes at inopportune times, yet he's still the same Doctor, with his vast knowledge of the universe and an innate need to help those in trouble.

The regeneration process itself is not an easy one, and the season's first episode (a holiday story called "The Christmas Invasion") has the Doctor recovering slowly on present-day Earth. After that, it's back out into the universe as the Doctor and Rose travel 5 billion years in the future to a planet called New Earth, team up with Queen Victoria to battle a werewolf on the Scottish moors and face off with clockwork robots at the court of French King Louis XV.