Definitely the face of someone with nothing at all to hide.
We open with a close-up on an anxious-looking Ianto straightening his tie and taking a steadying breath. This is the first time we can really see him up close, how pale and gaunt he is. He steps out of the lift and through the cogwheel door into the Hub, where Tosh, Owen, Gwen and Jack are playing a two-on-two game of basketball, with Myfanwy shrieking in the background. (Myfanwy, in case you’ve forgotten, is the pteranodon.) Everyone’s happy and laughing, and Gwen steals the ball from Jack and throws it up to Owen on the second level for him to drop through the hoop. It’s totally an illegal move, but whatever, they win! So the first round is on Jack, and they all cheerfully argue about it as they leave, passing Ianto without a glance, even Jack, who throws the basketball at him as they go. He catches it, and when they’re gone, he drops it and runs down into the Hub. He is definitely up to something secret, and he’s terrified about it.