Andromeda is giving Dylan a physical check-up. She says that he is mostly fine, but a little out of shape. Suddenly, Andromeda's screen changes to a recording of Dylan and Sarah's last goodbye, which replays over and over.

Rommie walks up to Harper in the hallway, and grabs his hand, informing him that it is for lie detection. She asks him if, when he built her, he included any controls that might allow him to do things that she would not know about.

Harper suddenly stares over Rommie's shoulder. She thinks that he is trying to distract her, but he insists, and she looks to see a cat. She is surprised by this, as cats have been extinct for a thousand years. Harper and Rommie chase after the cat, following it to a machine shop, where it is lost. As they are looking around, a vortex opens up and starts to suck Harper in. Rommie grabs him, until the vortex closes.

Dylan is in the Ready Room, and finds he is unable to contact Andromeda. Beka bursts in, saying she thought that Dylan had called for help. Dylan realizes that something strange is happening, and calls shipwide for the rest of the crew to meet him on Command.

Trance is the first to the Command Deck, where the view screens are showing, over and over, a sun exploding. Trance, seemingly quite disturbed, tells Andromeda to turn it off.

Tyr is the last to arrive, and claims that he just saw his child, sleeping.

Andromeda reports that there have been several attacks on nearby planets by Magog, Nietzscheans, and a general rise in criminal activity, but that the perpetrators have all suddenly disappeared. She also reports distress calls from several nearby ships. Only one ship's message is at all intelligible, and, from that, Andromeda can only understand the words "nightmare", "terror", and "invisible". All of the ships that were attacked had their most complex and powerful power source removed.

Rommie is missing, and Andromeda cannot find her. Andromeda reports that there are several decks that she cannot contact, and that there are vortices opening and closing throughout the ship.

Tyr suspects another attack by the invisible aliens that abducted him. He and Dylan begin to search the ship for Rommie.

A vortex opens up and begins to suck Tyr in, but he grabs a door frame and holds on. Dylan comes running at his call, and, at a loss for a way to help, fires his forcelance into the vortex. It closes, and Dylan teases Tyr that he saved him.

Andromeda finally manages to contact Rommie, who says that she is going to go after the aliens, both to save the crew and to get revenge.

A vortex opens up near Rommie, who insists that everything is under control. Several Derevos (the aliens from the Commonwealth Charter signing) appear, and attack Rommie. She is holding her own, and the aliens that she kills disappear. Dylan and Tyr rush to help her, but before they can get to where she is, four Derevos overpower Rommie, short out her circuits, and carry her through the vortex.

Dylan and Beka go out in the Maru, to search the area of space near the Andromeda. With the ship's censors, Harper detects a nearby energy wave. They look to Trance for a "guess" as to what is happening. She fires a barrage of missiles, narrowly missing a Derevo's ship that appears nearby. More ships appear, and begin to attack the Andromeda and the Maru.

Beka pilots the Maru back to the Andromeda, but the Maru has suffered a great deal of damage.

Andromeda detects a nearby planet with a massive energy signature, and indicates that she has traced Rommie to this planet. She says that the surface of the planet is uninhabitable, but there is a complex of tunnels beneath the surface.

Tyr suggests that they should forget about Rommie, but Harper protests. Tyr allows that he would welcome the chance to exact revenge on the aliens. Dylan and Tyr board a couple of slipfighters.

Beka asks Trance if she knows who the creatures are. Trance's answer is long, confusing, and uninformative. One of the creatures appears on the Command Deck and grabs Harper. Beka and Trance shoot it, and it falls to the ground and disappears. Andromeda detects an energy source on the ship, and Harper and Trance go to investigate.

Dylan and Tyr land the slipfighters in the tunnels, as close as they can get to the power source. Dylan tries to find out what Tyr remembers about the Derevos from their last encounter, but he does not remember much.

An alien surprises Trance and Harper, but Trance shoots it.

Beka is on Command, when the viewscreens suddenly change to a recording of her and Tyr kissing, while they were under the control of the Derevos. Beka is displeased by this.

Dylan and Tyr hear a strange noise, and find two Derevos, who are phasing in and out, but standing still. Tyr speculates that they may not realize that they are visible. Dylan and Tyr shoot them, and they fall and disappear.

As Dylan and Tyr are tracking the power source, they come to a bridge over a deep chasm – the power source is on the other side, so they start across, when they are attacked by two Derevos. They each shoot one, and the Derevos fall into the chasm.

Dylan traces the power source to a door. Before he can decide on a course of action, Tyr shoots the door down. Behind it, they find Rommie, bound to a machine, with tubes and wires attached to her. She says that the aliens are using her to focus their power source, but the generator is not online yet. More Derevos attack, but Dylan and Tyr fight them of and free Rommie. She says that "something big" is coming, and it is "in a hurry".

Beka sees several Derevos ships appearing, and tells Dylan (over comms) that there is a new Tunnel opening, with more ships coming through. Harper and Trance return to Command, and they fight the Derevos' ships, but Andromeda takes heavy damage.

Tyr, Dylan, and Rommie take stock of the weapons and equipment they have at hand. Dylan asks Rommie to build a time bomb to destroy the generator. She does so, and sets the timer for 20 minutes. As they are leaving, they are confronted by several Derevos on the bridge. They fight, Tyr's gun is knocked over the side, and Dylan finds himself hanging from the edge of the bridge. Tyr throws the Derevo that is attacking Dylan off the bridge, and helps Dylan up, pointing out that, this time, he saved Dylan. The three of them make it back to the slipfighters.

The Andromeda is still under attack, and Dylan tells Harper (over the radio) to get his "jaws of life" invention that he used the last time they fought the Derevos. He heads to the machine shop to re-assemble it.

The slipfighters are attacked by Derevo ships, but the Andromeda comes to their rescue.

As the slipfighters dock, more ships are coming through the tunnel, and Andromeda detects that there is a staging area behind it. Beka realizes that the Derevos that attacked them were not left behind from the original attack, but were an advance group for a new invasion.

Harper is worried that his device will draw the Derevos' fire, but Dylan tells him to turn it on. He does, and the alien ships attack the Andromeda.

Dylan orders Beka to retreat, and says that the force of the tunnel closing will push them to safety, and it will be closing soon, because they are about to lose their power source. The bomb explodes, destroying the generator, which causes a chain reaction, resulting in the destruction of the planet. The tunnel beginds to collapse, sucking in the alien ships.

A vortex opens on Andromeda's Command Deck, but as they move away, it closes.

The tunnel collapses completely, and the fleet is gone. Harper wonders about what is on the other side of the tunnel. Trance gives another cryptic answer, mentioning "bad dreams" and "the abyss", and saying that she knows it was "a test".

Harper welcomes Rommie back, and she lets him give her a hug. Harper tells her that he did not do anything to her (referencing their earlier discussion), and she can tell that he is not lying.

A single Derevo appears on the Command Deck. Before anyone can react, it kneels in front of Dylan, offering him a dagger. Dylan takes it, and the Derevo collapses and disappears. Dylan comments that they must have passed the test.