The SGC receives an incoming traveler alert, but just before they can determine who it is, there’s a bright flash--along with an accompanying sound like a muffled explosion--just before SG-1’s G.D.O. is picked up and they’re allowed through. When SG-1 returns, they say that they haven’t seen or heard anything out of the ordinary. As General Landry debriefs SG-1 on their previous mission, Teal’c refers to recent intelligence given to them by Selmak. When a shocked Landry reminds Teal’c that Selmak is dead, an equally shocked Sam informs him that both Selmak and her father--within whom Selmak resides--are alive and well. Just then, the SGC gets another visitor through the gate, and it turns out to be…SG-1.

An examination of both teams reveals that they are all SG-1. They’re human, and match right down to the DNA. Since the second SG-1 team arrived at their expected time, and they jive with their surroundings, it’s determined that they are the "real" SG-1. The other SG-1 is a team from a parallel universe who somehow wound up in this universe when a "bridge" was created, connecting the two universes via the wormhole. But if only the problems ended there. The "bridge" between universes causes more and more alternate SG-1 teams to show up through the stargate, which fills the base with multiple Mitchells, Sams, Teal’cs and Daniels. But not all of the alternate SG-1 teams are the same--one of them has a member by the name of Dr. Janet Fraiser.

Ripple Effect is an enjoyable little affair with plenty of twists and turns, especially in its second half. Just when you think it’s going to be strictly a scientific jaunt, it then becomes a fun thriller set aboard the Prometheus, with SG-1 fighting a unique enemy: themselves. Plus there’s the added poignancy for long-time fans of having a pair of deceased characters--Janet Fraiser and Martouf--return in a storyline where their presence still makes sense. While our Sam tries to rekindle her lost relationship with Martouf, Brad Wright's script offer plenty of teasing moments about the various other Samanthas (all of whom are seen working together in a humorous scene), who are either married, or on maternity leave. Overall, Ripple Effect is a gratifying romp for both the casual and long-time fan of SG-1.