The "secret passage" Ziwei mentioned was actually the dog hole in the back wall of the Imperial Kitchen.
"This is called a 'dou'!" she corrected me, her face flushed. "Emperor Kangxi crawled through it when he was a boy..."
I stared at the opening, half-hidden by weeds and reeking of swill, and suddenly understood the mood Little Swallow had been in all those years ago. But the glow of torches behind us was growing brighter, and the clanking of the guards' armor was clearly audible.
Chapter 238