Behavior under extreme situations is a traditional movie set-up. Dump a few people into a pressure cooker and see how fast the top blows off. David Koepp, the writer who vaulted to instant success with screenplays for Jurassic Park and The Paper, gets his chance to see his vision to the end in his directing debut, The Trigger Effect. Considering the level of professionalism reflected in the film, Koepp will no doubt spend equal time behind the camera and in front of the keyboard.

Koepp displays a fine feel for filmmaking in the opening scenes of The Trigger Effect. The sense of menace is pervasive through the use of camera perspective and fine cutting. I can think of four or five scenes when I waited for a violent explosion, only to be lead through another door of the screenplay. Once the heart of the action is revealed, The Trigger Effect fails to maintain the intensity that the spare opening scenes generated.

The film makes it’s dark turn when a power outage blacks out a chunk of Southern California. There is requisite looting, security questions, guns and food at a premium. In the midst of the madness, young marrieds Matthew and Annie are under the gun when their baby runs a high fever and Matthew has to enter the urban jungle to secure medication. He finds the city in confusion with the basest elements taking control.

After surviving that crisis, their small pot boils over when good buddy Joe arrives to share the black-out, gun in hand. Joe’s the wild card. He adds a dram unwanted tension. With Joe in the equation, both Matthew and Annie add up to a different sum. Before you can count to ten, there’s murder in the neighborhood and the Trigger Effect takes an unexpected turn into a road movie.

Guns continue to play a big part in Koepp’s tension filled screenplay, and though he travels from claustrophobic house and neighborhood onto the open road, he still manages to maintain the tension, though his attempts to link the chain of the screenplay seamlessly are not wholly successful.

Kyle MacLachlan and Elisabeth Shue are appealing as the husband and wife finding their way through an unexpected crisis. MacLachlan displays a bit more fire and emotion than screen audiences are used to from him, and it’s a welcome side of the actor. Shue, proving herself a consistently fine actress and important screen presence is not given enough material to work her special magic. Dermot Mulroney as Joe is given a tougher job trying to make the third man in a convincing portrait. Mulroney usually assays the easygoing screen charmer, but the edge Koepp expects from his never seems convincing. Perhaps it’s a fault of the screenplay, since there is no reason to believe that Matthew or Annie would find Joe attractive as a friend.

Watching The Trigger Effect is like visiting a restaurant that has lots of promise. You can sense the adventure of the chef, the use of the finest ingredients, but his dishes don’t quite come perfectly together . Excellent photography and editing help define the Koepp style. Given his skill as a writer, there’s every reason to expect a more polished film meal next time out.