- Kenneth Hein

NEW YORK Diet Mountain Dew will have its fans seeing purple beginning Aug. 10. The growing soft drink brand is adding the mixed berry-flavored Diet Mountain Dew UltraViolet to its portfolio for the next three months. The launch marks the first time PepsiCo is introducing a Diet Dew-only line extension.

Regular Dew, meanwhile, announced today it is teaming up with Paramount Digital for Circle of 8. The "studio-quality" interactive thriller -- which invites viewers to participate in the narrative -- will debut online in October.

In a category that is struggling, Diet Dew is one of the few bright spots. It was the best performing Top 10 carbonated soft drink brand in the first quarter of the year, per Beverage Digest. Its sales volume was up 7 percent. Regular Dew didn't fare as well. Its volume was off 2.9 percent. The rest of the category shrank 3.1 percent.

The Dew portfolio remains a priority for PepsiCo because "both Dew and Diet Dew continue to be powerhouses and workhorses," said John Sicher, editor of Beverage Digest.

UltraViolet will be supported via TV and radio advertising developed by BBDO, New York. The work includes copy such as, "We're on your wavelength. Try new Diet Mtn Dew UltraViolet, the new Diet Dew made for you." A "First Taste" party was held, on Monday in Brooklyn, N.Y., for Mountain Dew followers on Facebook and Twitter, as well as select fans.

Full-calorie Dew is making a splash on MySpace, where Circle of 8 will debut before being distributed to other sites. Dew will be integrated into the film, "going far beyond traditional sponsorship and brand integration models," said Frank Cooper, CMO of sparkling beverages for Pepsi-Cola North America, in a statement.

The film will allow viewers to determine the characters fate. Cooper said, "Mountain Dew will play a critical role in evolving the storytelling experience through Circle of 8."