But about three o'clock I had a sudden inspiration.
The name Julia Czechenyi flashed across my memory.

Scudder had said it was the key to the Karolides business, and it occurred to me to try it on his cypher.
It worked.

The five letters of 'Julia' gave me the position of the vowels.

A was J, the tenth letter of the alphabet, and so represented by X in the cypher.

E was XXI, and so on.