Madame Dorothea's Portal dumps Clary on the other side of the fence from Luke's home/bookshop, Garroway Books. Phew. Thank goodness she didn't end up on the Planet Krypton or anything.
Jace plops down on top of Clary. Once they untangle themselves, he tells us that Portals don't have a set end point; they go wherever the traveler has on her mind.
Deducing that Luke isn't home, Jace hops the fence... and lands on someone on the other side.
Simon had been hiding in Luke's bushes, watching what Luke was up to because he (Simon) thought he (Luke) was acting suspicious.
Looks like Simon saw Luke packing a duffel bag full of glowing weapons. And Simon thought that was strange. Wait. Don't all booksellers tote around an arsenal of glow-in-the-dark swords? Oh wait, that's librarians.
Clary and Jace fill Simon in on all the complicated Shadowhunter business that Clary's had to learn over the last six chapters. So Simon's got a bit of catching up to do.