Even though you might think the doctor suspects something all along, he doesn't. The banker goes against his principles and gives them the 50,000.
Eve has remained enigmatic, however, when the doctor breaks off with his Montreal girlfriend and goes to tell the news to Eve, he is surprised when she already has heard about it so she simply tells him everything. He is angry and tells the group off and says he's done with them.
They're up a creek because the factory reps have just come to finalize the deal and they have no doctor. The doctor does some deep thinking, and at the last moment bursts into the café just at the right moment and apologizes for keeping them waiting, and asks where he should sign.
Thanks Mary M!