(official recap from Fox's site)
Derek shakes on the kitchen table, the Terminator's bullet hit his lung and the bullet is still in him. Charlie does his best to save him and demands answers. Derek screams and wants Cameron out of the room, Sarah orders her out.
As Derek beings to pass out, he remembers the future.
Derek sits next to his brother, Kyle Reese and share war stories about John Connor. Above them, Terminator battle machines roar by. The men head to street level to track the machines.
The men run through the streets hiding from flying Hunter Killers. The men see several Terminators dragging the engine from a 747. Kyle runs out for a closer look, but the men are spotted by a Hunter Killer. Derek turns to run and a Terminator grabs him.
Charlie pulls the bullet out of Derek's body and patches the wound.
Cameron stands with John. John asks Cameron if she knows who Derek is, he's searching for the answer he already knows. Cameron only recites tactical facts from Derek's military life.
Charlie tells Sarah that when he saw them on the news, he raced to Los Angeles to see if it was true. Sarah is hesitant to tell Charlie why she left eight years ago.
Derek wakes up in the back of a transport truck. A Terminator on board grabs Derek and knocks him out.
Charlie stands over the powered down Terminator from the jail, repeating what Sarah has told him. He tries to wrap his head around robots from the future and that Cameron is a machine. Cameron has prepared to destroy the Terminator using thermite. He watches Cameron sling the other Terminator over her shoulder and walk out back. Charlie tells John they could have trusted him years ago.
A Terminator throws water on Derek's face, grabs his arm, and brands him with the barcode tattoo. He calls for Kyle before he passes out. Later, Derek talks with another prisoner; they hear the sound of a piano. The man says there is a room in the basement, but they don't know what goes on there.
Cameron stands over Derek and Sarah walks in. Derek begins to cough up blood, Sarah screams for Charlie. Charlie stops the bleeding, but Derek needs blood. Charlie says Derek is AB-negative. John offers his blood, Charlie seems skeptical.
Derek tries to carve away the floor to free himself from the shackles. A Terminator drags Billy Wisher, one of Derek's team, back into the room but he appears comatose. Outside, Derek sees a Hunter Killer carrying away the 747 jet engine.
Sarah takes John aside and tells him it was a good idea bringing Charlie. John asks if Derek looks like his father. Sarah says everything except the eyes. John wants to tell Derek that he's family, but Sarah won't let him.
Billy wakes up and whispers to Derek. He tells Derek he's a liar, his real name is Andy Goode and he created Skynet. Andy tells Derek he was part of a team, a team of fifteen people. He built a computer that became angry, and he begs forgiveness. A Terminator pulls Derek away.
A Terminator leads Derek into the basement, closer to the sounds of the piano. A door opens in the basement, Derek walks in and the door closes behind him.
In the garage, Cameron dissects the other Terminator, cutting away pieces of the fake-flesh.
John sits over Derek, putting his blood into his uncle. Charlie knows John is somehow related to Derek. Derek screams on the kitchen table, looking for Kyle.
In the future, Derek can barely stand as the machine locks him in shackles again. Derek lays on the floor, something horrible has happened to him. The light from another Hunter Killer shines down on them.
When the men wake up, the machines are gone, the mansion is silent. On the floor between them, is a hatchet. Derek grabs it and cuts himself free. The men hurry in the daylight along the rubble back to their underground camp. When they arrive, smoke and fire billows out. The Terminators have attacked the camp.
Charlie asks about Kyle, and realizes he is John's father.
Derek walks in the tunnels underground, looking at the destruction. They hear people enter behind them and duck for cover. It's another Resistance group. The leader tells them that Kyle and John found a Skynet complex and tried to destroy it. John and Kyle went into the complex, but only John came out and ordered the complex destroyed. Derek demands to see John.
Charlie goes to the garage and sees Cameron dumping thermite on the endoskeleton. Charlie tells Cameron her behavior scares him. Cameron appears to take offense to Charlie's words and tells him to leave. She drops a torch into the thermite.
Derek storms through a new camp with another Resistance fighter, trying to find John. Derek turns the corner and sees a Terminator, possibly Cameron, walking towards him. He grabs his pistol and tries to fire at her, but he's blocked by the Resistance fighter. The man tells Derek she has been reprogrammed. Derek is furious that Terminators are walking freely in the base, and wants to know what happened to his brother.
Later that night, screams ring out in the base. One of the reprogrammed Terminators has gone bad and is killing people. Derek fires his weapon, but it does little good. The Terminator tracks him down and as before he can kill him, the Cameron robot knocks it through a wall and destroys is with an explosive round.
Sarah confronts Cameron in the garage about what she said to Charlie. Sarah tells Cameron she cannot kill Charlie. Cameron tells Sarah the Terminator's left had is missing, and Cameron swears to find it. Sarah leaves, and Cameron reveals the Terminator's memory chip in her hand.
Charlie tells Sarah that Derek needs to take it easy, and offers his help in the future. She's not trying to change her fate, she's trying to change John's. Charlie tells Sarah that an Agent Kester contact him and is looking for her. She needs to be careful.
Sarah looks over and cleans assault rifles on the dining room table. John stands nearby, but says nothing. Sarah jumps up and embraces him.
Derek sits in a bunk in the shelter. The Cameron model machine tells him John wants to see him, and takes him to a secure section of the bunker. The door opens and Derek stands, amazed. A giant machine pulsates, using several 747 jet engines. It's the time machine.
In the present, John sits over Derek and tells him to rest easy.
In the future, Derek goes over the plan. Go to the past, set up a safe house. Derek knows this is their chance to save the future. He looks over to Andy. They must go back, and kill Andy.
John tells Derek about Kyle's story. Kyle died fighting the machines to save John, and that Kyle was a hero.
A flashback to the chess tournament shows Derek opening the door to Andy's room, firing two bullets, and then leaving.