"See that girl?"

A plainly-dressed young woman carrying a violin-case crossed the
street in front of our window.

"I see her," said I. "What about her?"

"That's Omega's second daughter."

"Oh, Omega," I murmured. "Haven't seen him for ages. What's he doing
with himself? Do you ever meet him nowadays?"

Said Mr. Alpha:

"I happened to dine with him--it was chiefly on business--a couple of
days before I fell ill. Remarkably strange cove, Omega--remarkably
strange."

"Why? How? And what's the matter with the cove's second daughter,
anyway?"

"Well," said Alpha, "it's all of a piece--him and his second daughter
and the rest of the family. Funny case. It ought to interest you.
Omega's got a mania."

"What mania?"

"Not too easy to describe. Call it the precaution mania."

"The precaution mania? What's that?"