Sterling has video of that building from two hours earlier. Boy, it's a good thing there's always a traffic camera trained on the one door to this unfinished building. On the video, someone enters the building, and Martinez claims to recognize Thomas from the back of his head, even though he's never seen him. Sterling says the field unit will have the place surrounded within minutes. Simon pulls up and uses a crowbar to pop open a padlock so he can get in. If this is the same door, how'd the padlock get on the outside of the door?
Simon's inside alone as his team pulls up outside. Simon goes through the construction-y hallways calling out to Thomas and Sophia. On the outside, the SWAT team is yelling "Execute execute execute!" as they do. Simon eventually finds Thomas and Sophia and tells them the place is surrounded. But Thomas has a trap door he can climb down into. Simon thinks that trained federal agents will find that trap door in about ten seconds, but Thomas claims to have a plan. The camera shakes and dust falls from the ceiling. Thomas looks pensive. Sophia asks him what he's done. Simon wants him to call off whatever he's done, but it's too late. Thomas and Sophia climb down the ladder, and Simon decides not to go with them.
TEN YEARS EARLIER, Simon sneaks into the room of the old lady from before (who, you'll remember, is the young lady from even farther before) and gives her a sunflower. She seems pleased to see him. She asks if he loved her. He tells her, "I never stopped loving you. If it were up to me we would have gotten married. We would have had children. We would have grown old together." She tells him, "It was up to you." I like this subplot. It tells me something about one of the characters!
In the building (how's that for setting the scene?) Sophia continues to beg Simon to come with them. Nope. He pulls out his phone and orders his team to evacuate the building. He climbs a ladder (not the same ladder that Thomas and Sophia climbed down) and gets hit by falling concrete. The building collapses around him. An FBI agent falls down. Simon looks scared as a giant blue CGI whirlpool opens up underneath him. Hey, it's a hellmouth! Actually, it looks like the thing that teleported the plane in the first episode.
The FBI agent that fell down has some rebar sticking through his leg, and Simon attempts to help him. Another agent (Simon's pal from ten years ago when they were celebrating their graduation) shows up and helps out. They drag the wounded agent into the next room. It takes forever, but they get him to the door. Simon is right behind the other two when rocks fall and bury him.