San Jose, Calif. ? It’s the first rule of Hollywood, and it’s also a reminder for hockey fans who scarcely can believe the cinematic matchup in the Western Conference finals.

Nobody knows anything.

The Calgary Flames and the San Jose Sharks are flourishing despite lacking every supposed necessity for NHL playoff success. They have low payrolls, low-profile rosters and not much postseason experience — and both teams were widely expected to struggle, falter and stay near the bottom of the conference, where they finished last season.

But after surprising regular seasons and semifinal victories over Detroit and Colorado, Calgary and San Jose will open the finals today at the Shark Tank. One underdog story will continue, one dream season will conclude — but neither team is ready for the closing credits just yet.

“Who saw this one coming?” Sharks defenseman Kyle McLaren said. “These teams, who would have predicted it?”

In a league traditionally thought to be dominated by money and experience, it’s the most surprising playoff development since, well, last season, when Anaheim and Minnesota came from nowhere for a similar conference final.

But the Sharks’ success was years in the making. Goalie Evgeni Nabokov and five of their top seven playoff scorers were San Jose draft picks, and the young roster came together swiftly during coach Ron Wilson’s first full season.

“The idea that we can’t spend enough money to get here, that’s a crock,” Wilson said. “It’s how you manage your players, how you draft, how you develop, how you trade, how you coach. We’ve earned our opportunities by working hard. That’s how you get here, and that’s how these teams did it.”

The Flames also put things together in one season thanks to coach/GM Darryl Sutter, fired by the Sharks in December 2002 and hired by Calgary 27 days later.

“We felt in order for us to grow and get better, our team had to get younger,” Sutter said. “Making the playoffs is obviously every team’s goal, but we had to look at doing what we could do to make the playoffs, to become a playoff team, and not hurt us long-term.”