APO LEARNS THE AWFUL TRUTH ABOUT SOPHIA, AN AGENT'S LIFE HANGS IN THE BALANCE, SYDNEY AND NADIA BECOME CONCERNED THAT SLOANE'S OBSESSION WITH RAMBALDI MAY HAVE BEEN RENEWED, AND JACK HAS AN UNSETTLING MEETING WITH KATYA DEREVKO, ON ABC'S "ALIAS"

Guest Starring are Angela Bassett ("How Stella Got Her Groove Back," "Waiting to Exhale," "What's Love Got to Do with It") as Hayden Chase, Sonia Braga ("American Family," "Kiss of the Spider Woman") as Sophia and Isabella Rossellini as Katya Derevko

"The Descent" - After learning the awful truth about Nadia's childhood caregiver, Sophia (Sonia Braga, "American Family," "Kiss of the Spider Woman"), APO races to track her down while an agent's life hangs in the balance. Meanwhile Sydney and Nadia question Sloane's trustworthiness now that his obsession with Rambaldi may have been renewed, Jack has an unsettling meeting with Katya Derevko (Isabella Rossellini), and Vaughn asks Jack a surprising and momentous question. Angela Bassett guest stars as Hayden Chase, on "Alias," WEDNESDAY, MAY 18 (9:01-10:01 p.m., ET), on the ABC Television Network.

Editors please note: This episode, along with "Search and Rescue," will air as a two-hour program from 9:01-11:00 p.m., ET.

"Alias" stars Jennifer Garner as Sydney Bristow, Victor Garber as Jack Bristow, Ron Rifkin as Arvin Sloane, Michael Vartan as Michael Vaughn, Carl Lumbly as Marcus Dixon, Kevin Weisman as Marshall Flinkman, Greg Grunberg as Eric Weiss and Mia Maestro as Nadia Santos.

Guest starring are Angela Bassett as Hayden Chase, Isabella Rossellini as Katya Derevko, Sonia Braga as Sophia Vargas, Jared Poe as young agent, Jeremy Brandt as lead CIA agent, Jeff Yagher as Greyson Wells, Braeden Marcott as salesman, Nick Jameson as Lazlo Drake, Jodi Fung as nurse and Andrew Divoff as Kevlar vest.

"The Descent" was written and directed by Jeffrey Bell.

"Alias" is broadcast in 720 Progressive (720P), ABC's selected HDTV format, with 5.1-channel surround sound.

A TV parental guideline will be assigned closer to airdate.