A Prince of the Captivity by John Buchan

Adam came out of prison in March 1914. His lawyer had seen to the preliminaries, and Camilla intended to divorce him for desertion under Scots law. He had settled upon her most of his income, leaving himself one thousand pounds a year, apart from Eilean Bàn. She ultimately married a hunting baronet in Yorkshire, and passed out of his life. The island he let for a further term of seven years to its former tenant. If he was ever to return there, he had a heavy road to travel first.

Most of the summer was spent in getting back his body to its former vigour, for the effects of a long spell of confinement do not disappear in a day. He took rooms at a farmhouse in Northumberland and set himself to recruit his muscles and nerves as steadily as if he had been preparing for an Olympic race. He spent hours daily on the moors in all weathers, and the shepherds were puzzled by the man with the lean face and friendly eyes who quartered the countryside like a sheep-dog. At one of the upland fairs he entered for a hill race, and beat the longest-legged keeper by half a mile. His mind needed no recruitment, for it had been long in training. He spent the evenings with his books, and once a week walked to the nearest town to get the London newspapers. He was waiting for a sign.