Trip, Reed, and Mayweather are sent to recover the scientists, not all of whom are eager to end their work abruptly. The official site calls the expedition "speleological," a word many may not be familiar with that refers to the scientific exploration of caves, where much of the episode takes place. In fact, the three ENTERPRISE actors had to get special repelling training at Stoney Point in Los Angeles County before shooting their underground scenes.

"For the cavern they're working in, the art design team didn't just erect rocky facades," says the report. "[They] filled it with a slew of stalactites and stalagmites and other exotic mineral deposits (all fabricated in the shop nearby, of course) along with scientific equipment."

The secondary storyline in "The Breach" centers on the rescue of several aliens from a damaged vessel, one of whom refuses treatment from Doctor Phlox because his species -- the Antarans -- have some unsettled bad blood with Denobulans. 'Hudak', as he's called, is played by guest star Henry Stram, and is joined by three other STAR TREK newbies as the Denobulan scientists: Mark Chaet, D.C. Douglas and Laura Putney. Jamison Yang plays a crewman and extras round out other refugees and Sickbay patients.

"The Breach" was penned by Chris Black ("Cease Fire") and John Shiban ("Minefield"), from a story by Daniel McCarthy. The episode will air on UPN April 23rd. You can read more of the production report here.