"What," Don asks, blandly sardonic, "did you think this was?"

There are gaps--yawning gaps--in what he's told Gene, partly because there are some things you can't tell people. Nobody's going to believe they're in a prison until they've rattled the bars (and even then...). Other things--the map, the population of sleepwalkers, the hatches--he's left out because he can scarcely stand to consider them himself.

With this in mind, he offers, "I can tell you now or as you walk."