The theory was plausible, but Inspector Whyland knew well enough that so far he had not a fragment of real evidence with which to support it. But, unless he were to adopt the suggestion of Mr. Ludgrove, that some homicidal maniac was responsible, Whyland could see no alternative. The lack of motive was so extraordinarily puzzling. The murders had been utterly purposeless, and the only possible theory could be one which took full account of this fact. And then again, how account for the despatch of the numbered counters? If the murders had been inspired by irresponsible impulse, what had been their object?