BBC America's top-rated series, Torchwood, exploded into season two with guest star James Marsters (Buffy) and now episode six brings a highly anticipated cross-over with Doctor Who's Martha Jones (Freema Agyeman) and a menacing guest role for Alan Dale (Ugly Betty, The O.C.).

Created by Russell T. Davies, lead writer on the current "Doctor Who," the high-octane second season has taken a stronger "Torchwood" team through dare-devil action, temptation, heartache - and now they face a life changing event.

"Torchwood" season two airs Saturdays, 9:00 p.m. ET/PT.

Captain Jack (John Barrowman) calls on Martha Jones to join the Torchwood team Gwen (Eve Myles), Owen (Burn Gorman), Toshiko (Naoko Mori), and Ianto (Gareth David-Lloyd) to help investigate mysterious deaths. When the trail leads to a sinister medical testing center, Martha must go undercover. But has Torchwood underestimated how far the testing center's director, Professor Copley (Alan Dale) will go to find medical breakthroughs? How safe is the Torchwood team?

Following episode six, the Torchwood team members, deep in shock, have to face their darkest hour. In an effort to put things right, Captain Jack unleashes a primal force that uses Torchwood as a conduit to wreck havoc across Earth, aided by the Weevils and their newly-appointed King. Then the night before her wedding, Gwen is juggling work with her bachelorette party, when an alien shape shifter leaves her carrying more than she bargained for. As everyone gathers for the ceremony, Jack must destroy her big day, unless one of the three mothers present finds a means to stop him.

Before the season ends, James Marsters returns as charismatic-but-psychopathic Captain John Hart, along with guest appearances by Richard Briers, Ruth Jones and Nerys Hughes.

Alan Dale on his guest role, "I am thrilled to be working on 'Torchwood' and delighted to be in England again. I am a huge fan of British television drama."

Freema Agyeman on her three episode arc on Torchwood, "It's a huge new challenge and a wonderful opportunity to develop and expand the character of Martha Jones."

BBC America's new Supernatural Saturday line-up kicks off with Doctor Who, season three, on Saturdays 7:00 p.m. ET/4:00 PT, followed by an encore episode of Torchwood at 8:00 p.m. ET/PT and the U.S. premiere episode at 9:00 p.m. ET/PT.