Finn and Rey pilot the stolen Millennium Falcon to escape the First Order, but are captured by Han Solo and Chewie. After a Mexican stand-off with two other teams of smugglers, Han takes his friends to the planet of Takodana to meet an old friend. Rey is distracted by voices, and enters the depths of the city where she uncovers Luke Skywalker's lightsaber.
The First Order raise the stakes and send out the full power of their planetary weapon which destroys a complete system of the Republic, the ruling power in the Galaxy.
Two spies (one for each side) inform their masters of the whereabouts of the stowaways and BB-8 droid, but the First Order are quicker on the scene. Kylo Ren tracks down Rey, finds that she has seen the map, and takes her back to his ship.
The Rebels, led by fighter-pilot Poe, show up and help turn the tables, but Kylo escapes with his hostage, and takes her back to the Starkiller base.
Leia shows up, and patches things up with Han. And we find out that Kylo Ren is Ben, their son. They discuss a plan to stop The First Order, and need the help of Finn to show them where a platform is that they need to destabilize and stop the giant cannon from firing.
Meanwhile, Kylo takes off his helmet again (which is one of the worst moments of the movie - they should have chosen any other actor, or even just cut his hair a bit and given him a few scary scars), to reveal the most unthreatening bad guy in recent cinematic history. Rey knows him instantly. He tries to use the Force to read Rey's mind, and she resists in a scene with a lot of frowning, pointing and heavy sound effects (and with the sound turned off would look a bit weird). He gives up.
Now she has realised she has powers, she tricks the guard on duty and escapes.
The Falcon enters the planet's atmosphere. Finn, Han and Chewie get into the facility and, thankfully like on the Death Star, all the action on the entire planet can be done in a few rooms and sets where all the characters assemble. They kidnap Captain Phasmo (really), who puts up even less of a fight than a typical stormtrooper, and they can lower the shields.
They soon enough meet up with Rey, which is handy, then plant explosive charges around important structural columns. Han soon spies his son, Ben, and goes to meet him on a middle of a walkway. Ben wants his help, and is about to hand him his lightsaber, when he changes his mind and stabs Han. Han dies and falls off the walkway. Chewie screams/growls and hits Kylo in the hip with a shot from his bowcaster, before they escape.
Outside, Finn stands up to Kylo and gets in a few good shots against somebody who really should have better lightsaber skills, but finally is slashed across his back. Rey then steps up and does a good job, even managing to better his use of the Force and give him a good lightsaber slashing before a chasm emerges between them.
It's getting pretty dark by now, and the timer should have hit zero a while back. Chewie shows up to take away his pals. The explosives weaken the metal plate, allowing the few remaining X-Wings the opportunity to take it out, which then destabilizes the whole planet, and it even somehow completely blows up.
The Rebels meet up again at their base, and this time R2 wakes up. Together with BB-8 they join the plans together to show Luke's location. Rey and Chewie hop in the Falcon, where they land on a green mountainous planet, and Rey climbs the steps until she meets a bearded Luke Skywalker at the top and holds out the lightsaber. He just stares, motionless, for a while. (He really wanted the green one).