Out of the sun - Robert Goddard (First UK edition)

When Harry Barnett is anonymously informed that is son is languishing in hospital in a diabetic coma, he is certain there must be some mistake, since he does not have a son. But he soon discovers that he does. 

David Venning, now suspended between life and death, was a brilliant mathematician, working in realms of thought that only a handful of people on earth could even begin to comprehend.

The mystery of Harry's paternity is soon solved, but other, darker mysteries quickly supervene. David's tragic condition is taken to be the result of an accident or a suicide attempt. But his precious notebooks are missing from the hotel room in which he was found. And Harry soon discovers that two other scientists employed, like David, by Globescope Inc., an American forecasting institute, have died in suspicious circumstances. Perhaps David is actually the victim of an attempted murder. And perhaps the deaths of other Globescope staff are not the coincidences they seem. Pursuing the truth in England, Denmark and the United States, Harry finds himself entangled in several different kinds of conspiracy, none of which he should - in theory - be able to defeat. But as before in his life, Harry finds that circumstances and theory are not necessarily the same thing.