Liz, Max, Michael and Isabel were the only ones Liz saw getting killed in her vision, so they were the only ones who planned on leaving Roswell. Michael was leaving and he came to Maria's house to tell him how he had always loved her, since the first time he saw her. Took him long enough. Then he left. Earlier he had gone with Maria to a tarot card reader because Maria was trying to figure out what she really wanted (Michael or a normal life), and the psychic told Michael that he could save people he loved by trusting in love. He left the reading saying it was a bunch of cr@p, but after he left Roswell he saw suspicious black SUVs and pulled out the lovers tarot card he had been given. He then headed back to Roswell.

Meanwhile, everyone else was at graduation, but the gang thought the attack was coming in a day or two at a sci fi convention, not at graduation - there was a sci fi author as a guest speaker at the convention, and it was his inclusion in Liz's vision that lead them to believe the attack would happen there. They didn't know he was also speaking at graduation. When he showed up, the gang looked at each other, knowing they would have to do something. Liz, Max and Isabel all had snipers aimed at their heads (unbeknownst to them) when Max stood up, went to the podium, told the speaker to leave for his own safety (when the speaker wouldn't leave Max waved his hand over a piece of paper and changed the text to say "leave for your own safety") and started talking to the crowd. He made the lights go out and put a spotlight on himself, thus ruining the shots of the others but keeping himself a target. He stalled long enough to let the others get out (Isabel even said goodbye to her parents and a rushed goodbye to Jesse).

Just as Max was going to get shot, Michael comes bursting in on his motorcycle and makes all the lights go on, blinding the bad guys who had on night vision goggles. He rides up to the stage and gets Max, and they both escape.

Max, Michael, Liz, Maria, Isabel and Kyle all meet up in the hills again, and this time decide to leave together. Max renounced his throne and said that Michael was no longer his second and Isabel was no longer a princess - they were staying on earth forever. Earlier Liz's visions helped Max save a woman from being murdered, and he realized that using his powers to help people was just as good of a use of his abilities and life as ruling a world he didn't know.

Liz has already been proposed to by Max (he took a piece of charcoal and said "this is something I learned from Superman" and made a diamond in his fist using his powers), and accepted, and had said that she will be happy wherever he is (she had been accepted to Northwestern and he was going to go with her until they were all exposed) - so she was in. Kyle said he would change eventually too, like Liz did, due to Max saving them - thus he would go to be with "his own kind" when the change happened. Maria said she was going too - she wasn't about to let Michael get away after he finally admitted that he loves her completely. Jesse shows up in a van (conveniently after they say they'll need one ) and tells Isabel that he loves her and that he's going with her. He was willing to give up everything for her, but she said that she hadn't been fair - she had dragged him in without his knowledge, and that while his willingness to go meant the world to her and that she loved him, she couldn't do that to him. He put her wedding/engagement rings back on her finger, and asked her to meet him in Boston if she could, sometime in the future. She said she'd try, they kissed and hugged and said goodbye. The rest of them left while Jesse stayed.

On the road they met up with Mr. Valenti, and this is where we find out he finally got back into his first love, law enforcement. He's just a deputy, but he's happy. He says a tearful and touching goodbye to his son, and they hug. He then helps them get to Arizona (as an anonymous tipper he had told the govt guys that the kids were headed to Mexico). As they drive away, there's a voiceover by Liz, who has presumably been telling the entire story of what happened (since the first episode) in journal form, as a letter of sorts to her father. She tells him that she and Max are happy, and that they got married, and that they are all now on the road using her visions to help people. She ended by saying goodbye to her dad, and asking him to give the journal to her mom to read, then to Maria's mom to read, then to take it to the site where her husband had been born in the hills (near the pod) to burn it.

It was a bittersweet ending, as while it was filled with love and hope for the future, it was also filled with many goodbyes.