In the instant their eyes met, both Dr. Schneider and Shard widened their eyes, with Shard even reading a "What are you doing here?" in the other's gaze.
Indeed, Shard had informed the doctor about having to attend a rather formal dinner due to a commission from his firm, but he didn't mention it was the dinner at Lakeside Manor; nor did the doctor ask where it would be, probably not expecting Shard to show up at such a place.
Wanting to leave the card table and head over to the doctor, but the doctor, looking serious, subtly shook his head at Shard while continuing his conversation with a friend about the differences in the striking areas of silverware and goldware.
As they passed by the grape trellis, some people at the card table greeted friends who were accompanying Dr. Schneider.
Without any verbal conversation with Shard, the doctor discreetly gestured a series of rather complex hand signals, making sure Shard saw them clearly before leaving with his companion.