Alice looked through the grille. The duct doubled as a corridor; someone had welded a flat metal plate across the curve to form a basic floor. She tilted her head and listened. Faint echoes and shouts came from within, but nothing that hinted where the duct lead. A strong breeze sucked her forward and she had to hold her hair back with one hand. The grille and door were heavy steel mesh tied together by a rotary lock.