The title is a reference to the 1967 film Guess Who's Coming To Dinner starring Sidney Poitier, KAtherine Hepburn and Spencer Tracy. The survivor count shown in the title sequence is 39,673.
The episode begins moments after the conclusion of the previous episode, "Faith". The damaged Cylon Basestar has arrived at the same location as the Colonial ship Demetrius. Starbuck and Lt. Athena talk with Capt. Helo, the executive officer of the Demetrius, and remind him that both ships must jump at the same time so that they arrive back at the Colonial Fleet together. If the Cylon basestar arrives alone, the Galactica will attack the damaged basestar and likely destroy it.
The ships jump, but the Demetrius suffers a mechanical error which prevents it from jumping. The basestar arrives in the midst of the Colonial Fleet. Galactica launches its fighters and prepares to fire its weapons at the Cylon vessel. Just as the Galactica is about to fire on the defenseless Cylon vessel, Col. Tigh orders a halt to the attack, surprising Adm. William Adama. Just then, the Demetrius jumps into the battle and Helo communicates with the Galactica, advising the Colonial ship that the basestar is under the control of Capt. Thrace.
Lt. Gaeta, shot in the lower leg by Anders in the previous episode, is quickly taken into surgery aboard the Galactica. His leg is amputated below the right knee, traumatizing him.
Colonial troops board and take control of the Cylon ship. Adm. Adama, President Roslin, Col. Tigh, and presidential aide Tory Foster interview Natalie, one of the Sixes and leader of the rebel Cylons. She tells them of the Cylon civil war and the rebels' desire to find the Final Five Cylons, whom they believe will help them find Earth. Adama and Roslin express disbelief that the Cylon rebels can be trusted, but Natalie offers them proof of her goodwill: The "Final Five," she says, are somewhere in the human fleet. Natalie offers to take the Galactica to the Hub, which is a nexus of operations for all Cylon "resurrection ships." If the Hub is destroyed, the resurrection ships will cease to function and all Cylons will become mortal. Natalie tells them that the Hub is also where the deactivated Number Threes known as D'Anna Biers are located, who know the faces of the Final Five. Roslin and Adama agree to the plan.
Roslin, Athena and Caprica-Six once again have their shared dream in which Athena and Roslin chase Athena's half-human, half-Cylon child, Hera Agathon, through the opera house only to have Caprica-Six take the child into a brilliantly-lit auditorium. This time, however, Gaius Baltar is seen waiting at the entrance of the brilliantly lit door, walking away with Six and Hera. When Athena awakens from her dream, she finds Hera by her bedside. Hera whispers, "Bye-bye."
Starbuck visits Roslin and tells her that the Cylon Hybrid prophesied "the dying leader shall know the truth of the opera house". A startled Roslin asks for Thrace's help in unraveling the meaning of her vision, and Thrace agrees to do so.
Natalie is brought in to meet the Quorum. She tells the Quorum that the Cylon rebels have realized that death is an important part of life. The Cylons have begun to cherish every moment of the life, now that they realize they might permanently die. They no longer wish to engage in war, but need humanity's help to not only help them find Earth but also bring this realization to all Cylons everywhere. The stratagem seems to work, and Roslin gets the support of the Quorum.
Lt. Sharon Agathon arrives home in her quarters aboard the Galactica to find her daughter, Hera, coloring in a book. When she looks at the book, it's filled with childish drawings of the Cylon Six model and the number six repeated over and over. Athena looks up to find Hera gone. She runs through the ship, trying to find her daughter. In a corridor, Hera meets Natalie, who's being escorted by several Colonial Marines. Hera stops and Natalie kneels to greet the child. Athena rushes up and pulls a gun on Natalie. She announces Natalie will not take her child. Natalie says she does not want the child, but Athena shoots her twice and Natalie appears to die.
Aboard the Cylon basestar, Roslin, Baltar, and the leader of the Eights arrive in the Hybrid's room. Roslin orders the Hybrid reconnected to the Basestar's systems. As soon as the Hybrid wakes up, it screams "Jump!" The Basestar then jumps away from the Fleet.