His alarm caught the team coming back-- heading for the office upstairs rather than the fountain lift, which is a mercy because it gives Ianto more time to get Lisa hidden again.

He clears up Tanizaki's equipment then comes back to help the old man carry her back downstairs. Each man drapes a metal arm over his shoulder, three people trying to walk as one-- she's heavy and awkward, and it would be easier if she weren't also trying to help.

Ianto leaves them in the basement, knowing he's running out of time. "As soon as they're gone, I'll be down," he promises, then dashes back upstairs.