Na začátku 21. století navštíví v tomto sci-fi seriálu naši matičku Zemi mimozemská rasa Taelonů. Přijeli prý v dobrém, poznávat a studovat naši civilizaci a pomáhat lidem v boji proti nemocem, hladomoru a zločinu. Jejich tvrzení ale v mnohých vzbuzuje nedůvěru, a je zformováno hnutí odboje. V jeho čele stojí poručík William Boone, který je poté, co zachrání život jednomu z Taelonů, mimozemšťany najat, aby se stal jejich prostředníkem v komunikaci s pozemšťany. Boone tak dostává šanci odhalit skutečné důvody, proč na Zem Taeloni vůbec přijeli.

a.z.), Alan Van Sprang, Alex Poch-Goldin, Allana Harkin, Andrea Lui, Andrew Gillies, Andrew Jackson, Angela Asher, Angelica Lisk-Hann, Anita La Selva, Anne Marie DeLuise, Anne Openshaw, Anthony Sherwood, Arlene Duncan, Aron Tager, Ayumi Iizuka, Barry Flatman, Bill Lake, Blu Mankuma, Bobby Johnston, Bobby Johnston (a.z.), Bree Williamson, Brendan Connor, Brian Frank, Brittaney Bennett, Brooke Johnson, Bruce Beaton, Caleb Marshall, Caley Wilson, Carlo Rota, Cedric Smith, Chandra West, Charlotte Arnold, Chris William Martin, Christina Cox, Chuck Campbell, Claudette Mink, Colette Stevenson, Conrad Coates, Damon D"Oliveira, Dan Petronijevic, Daniel Clark, Daniel Magder, David Berni, David Calderisi, David Mucci, Dean Armstrong, Dean McKenzie, Derek McGrath, Derek Scott (herec, Derwin Jordan, Drew Nelson, Edie Inksetter, Elisa Moolecherry, Ellen Dubin, Eugene Clark, Fiona Highet, Fiona Loewi, Françoise Yip, Frank Moore, Geoffrey Pounsett, Guylaine St-Onge, Hamish McEwan, Hrant Alianak, Inga Cadranel, J.C. MacKenzie, James Binkley, James Downing, James Kee, James Kidnie, James Purcell, Janet Kidder, Janet-Laine Green, Jayne Heitmeyer, Jeff Geddis, Jeff Wincott, Jim Codrington, Jim Thorburn, Jodie Dowdall, Jody Racicot, John MacDonald, John Ralston, John Watson, Johnny Cuthbert, Jonathan Crombie, Jonathan Higgins, Jonathan Potts, Jonathan Welsh, Jonathan Whittaker, Joy Tanner, Judy Marshak, Juston C. Sharratt, K.C. Collins, Karen Holness, Kari Matchett, Kate Greenhouse, Kate Trotter, Katherine Ashby, Kathryn Zenna, Kathy Maloney, Katie Griffin, Ken Girotti, Kevin Jubinville, Kevin Kilner, Kevin Rushton, Kristi Angus, Kristin Lehman, Ksenia Solo, Landy Cannon, Lara Daans, Larissa Laskin, Len Doncheff, Leni Parker, Lisa Howard, Lisa Ryder, Lisa Ryder (a.z.), Lynne Griffin, Majel Barrett, Malin Åkerman, Maria Ricossa, Mark Burgess, Mark Humphrey, Mark Lutz, Markus Parilo, Martin Roach, Marvin Kaye, Matt Birman, Matt Gordon, Matthew Bennett, Maurice Dean Wint, Melinda Deines, Meredith McGeachie, Michael A. Miranda, Michael Cram, Michael Filipowich, Michael Rhoades, Michael Sarrazin, Michelle Nolden, Miranda Kwok, Monika Schnarre, Nigel Bennett, Nigel Bennett (a.z.), Noam Jenkins, Pamela Matthews, Park Bench, Pascal Petardi, Patricia Gage, Patricia Zentilli, Patrick Gallagher, Patrick Garrow, Paul Braunstein, Paul Johansson, Paul Miller, Paulino Nunes, Peter Keleghan, Peter MacNeill, Peter Mensah, Philip Craig, Phillip Jarrett, R.D. Reid, Rachael Crawford, Reagan Pasternak, Richard Chevolleau, Richard Clarkin, Richard Eden, Richard McMillan, Richard McMillan (a.z.), Richard Zeman, Richard Zeppieri, Robert Dodds, Robert Leeshock, Roberta Angelica, Robin Gammell, Rod Wilson, Roman Podhora, Russell Yuen, Sadie LeBlanc, Sam Malkin, Sandi Ross, Sarah Lafleur, Scott Gibson, Sean Bell, Shane Daly, Shannon Hile, Shaun Austin-Olsen, Shauna Macdonald, Shawn Ashmore, Shawn Lawrence, Shawn Roberts, Simon MacCorkindale, Simon Reynolds, Sonia Dhillon Tully, Stacy Grant, Stavroula Logothettis, Stephanie Belding, Stephen Bogaert, Steve Cumyn, Stewart Bick, Tamara Gorski, Thomas Mitchell, Tony Nappo, Trevor Blumas, Trevor Hayes, Tyrone Benskin, Vieslav Krystyan, Vince Corazza, Vladimir Jon Cubrt, Von Flores, Walker Boone, Wendy Lyon, William deVry (herec, Ylfa Edelstein