You can tell the crew is getting old when they start cruising around the galaxy with their left-turn signal left on.

Doppelgangers prove dangerous in Star Trek: Nemesis, the latest installment in the enduring sci-fi series.

As the movie opens, our crew has gathered to celebrate the marriage of two of its members, Commanders Riker and Troi. They're all there: Picard, Data, Worf, Geordi, Beverly Crusher and even her son, Wesley the Boy Wonder, who has no lines but grins a lot. It's all fun and games for a while, but of course that can't last.

The Enterprise is called to negotiate a peace treaty with the Romulans. When they get there they discover the new ruler of the Romulan Empire is a human named Shinzon and that he is a clone of none other than Jean Luc Picard himself, albeit one with about three times more lip than Patrick Stewart ever had.

"It's like looking in a mirror. A younger, veinier mirror."

From there we get treachery and adventure, space battles and psychological warfare and lots of soul searching for Picard on the subject of "How much like Shinzon am I?" It all makes for the best Star Trek experience since the crew took on the Borg in First Contact, which, granted, was only two movies ago, but still.

Which is not to say it's perfect. The dialogue in John Logan's screenplay could have done with a little sharpening, and a subplot involving the android Data and his less sophisticated brother/prototype — cleverly named B4 — feels a bit stilted. I would have also liked to see more development of the telepathic bond between Shinzon, his second-in-command and empathic ship's counselor Troi. It seems like there should have been something more to this storyline than Shinzon getting some virtual Betazed booty.

And, as usual, the rest of the crew has too little to do. Easy paycheck for Levar Burton; I don't think he even had to learn much technobabble for this one.

"I'm experimenting with the human behavior called 'farting'."

What did I like? There's an exhilerating excursion in a high tech dune buggy on a sun-baked, sepia-toned planet that's a lot of fun. The climactic space battle is dramatic and nail-bitingly exciting. And a new race called the Remans with a Nosferatu-like appearance are genuinely creepy.

But what made the movie for me was the relationship between Picard and Shinzon, and the performances of the actors who play them. Patrick Stewart, in what is reportedly his last spin as the starship captain, continues to give Picard the weight and complexity of a Shakespearean king. It's a little disconcerting to see him at the wedding celebration, joking with the crew and smiling more than he did the entire series, but once the story gets moving he slips on his familiar air of authority like a tailored coat.

Tom Hardy is delightfully sly and hammy as Shinzon. Fiery and determined with a touch of the resentful, damaged child and a faint echo of Picard, he makes a worthy and fascinating adversary.

As these two play their cat and mouse game, Data examines the concept of family and Riker defends his wife's honor, I found myself satisfied enough with this edition of the old reliable Star Trek franchise. If this is the last voyage of the starship Enterprise, at least they went out with style, high drama and some genuine fun.

Gorilla Pants rating: 3 out of 4 bananas