Beka, Tyr and Harper are dead, and the Andromeda has exploded.

We then see Trance, who is pruning a bonsai. "Okay. That did not work," she says.

Suddenly we go back in time, all the way to when the Andromeda has just entered space from a Slip portal. Everything is fine until the crew discovers something coming toward the ship. It doesn’t respond to hails, so Dylan orders it to be blown up. Missiles are launched, but they go right through the object like it wasn't even there. Harper then reports an intruder, which starts ripping through wires. Soon it disappears and reappears on the command deck and shoots Beka.

Again, we see Trance pruning. She decides to explore a different scenario.

Time is reversed again, and we are back at the beginning. Everything is the same. Harper asks, "Did we invite any guests?" and the intruder starts ripping through wires. Harper is told to leave the intruder alone but doesn’t listen. The intruder shoots Harper, wounding him. Trance does everything possible to save him; meanwhile, Rommie tells Beka and Dylan that the intruder’s armor is over 12,000 years old, and it seems to be going backwards in time. Harper's vitals become unstable and he dies. Trance re-lives that timeline again and again, but every time still ends with Harper dying. She has to try a different approach.

Time reverses yet again, with the same storyline unfolding, except this time Dylan tells Tyr to get the intruder. A fight ensues, Tyr is killed and the Andromeda explodes.

The time line repeats a fourth time, this time with Trance stopping Dylan from shooting at the incoming object by trying to explain what she knows, but as soon as she is done talking the intruder drops from the ceiling and kills Dylan. Chaos reigns as Trance wanders the ship, thinking. The Andromeda explodes.

Back in Trance's own timeline, where she is pruning the bonsai, Trance decides that Harper is the most expendable person. Trance jumps back into the storyline and Harper dies. Trance and Dylan have a heart to heart. She asks Dylan how he can deal with choosing one life over another. After a thought, Dylan decides that he knows all, and orders Beka to move the ship into Slipdrive. While in the Slipstream, the intruder can no longer disappear and reappear elsewhere on the ship, so Tyr tries to shoot it Ñ to no effect. The intruder opens the Slip tubes and Tyr shoots at it one last time. This only makes the intruder angry, and the Andromeda explodes.

Back in her own timeline, Trance can't figure out how to stop the Andromeda from perishing. She decides she has one last choice: Dylan.

The story rewinds to the beginning. As soon as the missiles miss the intruder’s ship, Dylan orders the Andromeda back into Slipdrive. This seems to work until Rommie notices that there is an intruder on the ship. Dylan runs down to belly of the ship and opens a gigantic set of doors to the vaccuum of space, which tries to pull him off the ship. The intruder appears and plays with the switches that control the doors. Dylan uses his force lance to impale the intruder and send him flying into the void. While Dylan hangs on with one arm, desperately trying not to be thrown into space, Trance suddenly appears, grabs his arm and pulls him to safety. Dylan closes the doors. Suddenly, the intruder reappears. Trance readies herself to fight but doesn’t need to. The intruder disappears as quickly as it appeared. Trance’s reasoning: "From its perspective, it still hasn’t found us yet."

Trance explains to Dylan how she goes through millions of different scenarios every second. Dylan asks her how she can determine if anything is real. Trance replies that she can't.