Alan Ross is a code-breaker with the British Secret Service.
I started to write 'agent' but realized that would be too big a stretch considering that the young man is only 15 years old and does not actually take part in field work. What he does is break the complex cyphers that he is given, often in remarkably short time, much to the amazement of the adults who come calling.
His father, John Ross, had been a police detective for many years and had earned a reputation with the underworld as someone to be feared and avoided. The last couple of years, however, he "ceased to be engaged in active police work" as he had been attached to the Secret Service and "his life these last few years had been more dangerous than ever before".
Ross Sr., codenamed Number 49, answers to Sir Anthony Fairway, head of the agency. It is Fairway who sees the tremendous potential in Ross Jr. and calls upon him ofte.
Alan Ross's entry into this line of work came when his father had given up trying to crack a short but vital intercepted message. In just a matter of a couple of minutes, young Ross had decrypted the text which gave his father the answer to how to snatch an international criminal and spy who was trying to sneak back into England.
Dear old Dad initially marked it up to a fluke but young Ross disagreed, telling his father, "I have always been interested in ciphers and codes. I have never found one yet that's made me really think". At that point, to let his son prove himself John Ross handed him a previously broken message, one that took the elder man "a whole after to decipher". Alan Ross had it cracked in a matter of a couple of minutes. The same held for several more tests. While his father was astonished, the teen shrugged off his gift as "just a way of passing an idle half-hour or so".
The wily Sir Anthony, when told of the boy's prowess, decreed that it was "the last brick in the structure [he'd] been patiently building for months". That plan included the establishment of a special listening post in an area of England that has the best reception. That place was the school of Mountcliffe, a prep-school of the finest reputation. In one of the buildings he sets ups a secret base where radio telegraph operators "tap many code messages passing between foreign governments, the messages passing between foreign secret service men, and very often the secret messages passing between gangs of international crooks". Those operators, however, had no skills in decoding these messages, which is where young Ross came in.
Ross is thrilled with the offer; not only can he expect to get loads of challenging puzzles to solve, he gets to attend a prestigious prep school, something that had been beyond his expectations.
He will find, though, that there will be a good number of challenges. He cannot let anyone, not fellow students or teachers, know what he is doing 'on the side' and he is expected to drop everything when an important message is received to be decoded. This will lead to punishments (caning!) and harassment and more. He will also find there are a good amount of skullduggery going on at that school.