Slowly, as he listened, an idea began to break in upon Jerry Stokes' mind. Ideas didn't often come his way. He was a thick-headed man, little given to theories, and he didn't know even now it was a theory he was forming. He only knew this was the way the case impressed him. The prisoner at the bar had never done it. But there had been scenes in his house--scenes brought about by Mrs. Ogilvy's conduct. Mrs. Ogilvy, he felt confident from the evidence he heard, had been given to drink--perhaps to other things; and the prisoner, for his child's sake (he had one little girl of three years old), was anxious to screen his wife's shame from the public. So he had suggested but little in this direction to his counsel. The scenes, however, were not of his making, and he certainly never meant to poison the woman. Jerry Stokes watched him closely as each witness stood up and told his tale, and he was confident of so much. That twitching of the lips was no murderer's trick. It was the plain emotion of an honest man who sees the circumstances unaccountably turning against him. There was another person in court who watched the case almost as closely as Jerry himself, and that person was the doctor who attended Mrs. Ogilvy and made the _post-mortem_. His steely grey eyes were fixed with a frank stare on each witness as he detailed his story; and from time to time he gave a little satisfied gasp, when anything went obviously against the prisoner's chances. Jerry was too much occupied, however, for the most part, in watching the man in the dock to have any time left for watching the doctor. Once only he raised his eyes and caught the other's. It was at a critical moment. A witness for the defence, under severe cross-examination, had just admitted a most damaging fact that told hard against Ogilvy. Then the doctor smiled. It was a sinister smile, a smile of malice, a smile of mute triumph. No one else noticed it. But Jerry Stokes, looking up, observed it with a start. A shade passed over his square face like a sudden cloud. He knew that smile well. It was a typical murderer's. "Mind you," Jerry said to himself, as he watched the smile die away, "I don't pretend to be as smart a chap as all these crack lawyer fellows, but I'm a straight man in my way, and I know my business. If that doctor ain't got a murderer's face on his front, my name isn't Jeremiah Stokes; that's the long and the short of it." He looked hard at the prisoner, he looked hard at the doctor. The longer and harder he looked, the more was he sure of it. He was an expert in murderers, and he knew his men. Ogilvy hadn't done it; Ogilvy couldn't do it; the doctor might; the doctor was, at any rate, a potential murderer. Not that Jerry put it to himself quite so fine as that; he contented himself with saying in his own dialect, "The doctor was one of 'em."