Suzaku demands a private meeting with Lelouch.
He has a bunch of questions he wants answered. But he doesn't know that Prince Schneizel's people are following him.
Lelouch is captured and Schneizel learns his identity.
He escapes, of course, and the battle begins.
Kallen is released and joins the battle. She fights Suzaku, and beats him.
This would be his end, but he's been geassed to live.
And they've installed an annihilation bomb on the Lancelot. It he discharges it over Tokyo, he will survive.
Nunnaly is vaporized in the blast.