All episode summaries were taken from tvtome.com

1×101 – 33
The Convoy of refugees is attacked exactly thirty three minutes after every FTL jump, leading many to believe there is a traitor in their midst.
1×102 – Water
Boomer wakes up in a storage locker soaking wet and carrying a bag with a bomb in it. Moments later, several explosions rip through the Battlestar Galactica bleeding her of 60% of her water. Now the crew struggles to find another source of water before riots threaten to destroy the convoy.
1×103 – Bastille Day
Lee has an idea to use prisoners to collect a new supply of water from underground on an icy moon, but the leader of a group of insurgents uses the opportunity to take some of the ship’s officers hostage.
1×104 – Act of Contrition
When a accident causes the death of 20 of Galactica’s fighter pilots on the hangar deck, Kara must train a new squad, bringing back painful memories for her and Lee.
1×105 – You Can’t Go Home Again
When Kara goes missing under enemy fire, Lee and his father stir up resentment by using too many of the Galactica’s scanty resources in their attempts to find her.
1×106 – Litmus
When an attack by some of the new humanoid Cylons reveals their existence, a tribunal is convened to determine if any more of them are hiding among the crew of the Galactica.
1×107 – Six Degrees of Separation
Baltar has an argument with Number Six over the existence of only one true god that leads her to disappear from his life. Soon after he is called to the bridge where he sees her standing there. He initially tries to pretend that he does not see her as is generally the case but soon learns that this Cylon is calling herself Ms Godfrey. She accuses Baltar of being the traitor responsible for the failure of the Colonial Defenses. She provides proof in the form of a disc that once analyzed will prove that he was responsible.
The chief and company are working to try and get the Cylon fighter to fly again but are completely unable to make it respond.
The president collapses while speaking to Baltar on the phone leaving the fleet in chaos.
Baltar tries to convince Gaeta to let him work on the decryption of the disc but he refuses. The computer finishes its analysis only to reveal Baltar planted the bomb he is accused of planting. He is arrested but freed after Gaeta runs another test to learn that the disc had been tampered with. He is freed and after apologizing to Number Six she returns to him.
Meanwhile, back on the glorious land of Caprica, Helo and Boomer continue their flight from their pursuers. The two have a few moments of tenderness followed by some hard core tongue action, while at the same moment Boomer back on board the Galactica opens her locker to see the word "CYLON" written in yellow on her mirror.
1×108 – Flesh & Bone
A copy of the Leoben Conoy (the Cylon that Adama killed in the mini-series) appears in the civilian fleet; Starbuck interrogates him. Before he was captured, Roslin had a dream with him in it, so she’s particularly determined to learn what he’s up to. Meanwhile, the Boomer on Galactica asks Baltar to test his new Cylon detector on her. And the Boomer on Caprica receives new instructions that she’s not comfortable with.
1×109 – Tigh Me Up, Tigh Me Down
Roslin’s suspicions regarding Commander Adama increase when he can’t be located during a military operation. Col. Tigh defends his friend despite being mad that he also didn’t know where Adama was. But everything is explained when the commander returns to Galactica with Ellen Tigh. It seems that the colonel’s estranged wife had been unconscious since the Cylon attack and is now awake and ready to reconcile. Tigh is thrilled to have his wife alive and back in his life; everyone else now turns their suspicions towards her.
1×110 – Hand of God
The fleet is facing a fuel shortage; the only possible relief comes from an active and heavily armed Cylon fuel refinery. Adama decides to launch an offensive against the base. This puts Lee on the spot since not everyone believes that he’s up to the challenge of leading the assault. Baltar, the resident "Cylon expert," makes a guess that could put the entire mission in jeopardy if he’s wrong.
1×111 – Colonial Day
Tom Zarek has himself nominated for the role of Vice President as an assassin is located on board the Cloud Nine Luxury liner. As tensions flare the cruel hand of politics leads to murder, and the election of the most unlikely Vice President.
1×112 – Kobol’s Last Gleaming Part 1
Galactica discovers a planet with the ruins of a past civilization. Adama wants to survey the planet and settle down there permanently. But Roslin has a vision that convinces her that this is Kobol and that she has a part to play in an ancient prophecy. Lee and Kara have a fallout. Baltar catches Galactica’s Boomer about to do something drastic. And Helo is unsure of what to do with Shannon.
1×113 – Kobol’s Last Gleaming Part 2
The crew of Raptor One crashes on Kobol. Baltar and Number Six look upon the face of the future. Starbuck reaches Caprica and finds the Arrow of Apollo. Adama orders the arrest of the President over her ordering Starbuck to retrieve the Arrow, and Boomer goes on one final mission to destroy the Basestar orbitting Kobol. Old Alliances fall, and new ones are formed, and someone is shot by Cylon agent…