“Let it sing—­God bless it!”

He turned, his youthful face reflecting the slight emotion in her gay voice.  Then with a grave smile he set his face straight in front of him and walked on beside her, the dark green pleats of the McKay tartan whipping his bared knees.  Clan Morhguinn had no handsomer son; America no son more loyal.

A dragon-fly glittered before them for an instant.  Far across the rolling country they caught the faint, silvery flash of Isla hurrying to the sea.

Evelyn Erith stood in the sunny breeze of Isla, her yellow hair dishevelled by the wind, her skirt’s edge wet with the spray of waterfalls.  The wild rose colour was in her cheeks and the tint of crimson roses on her lips and the glory of the Soleil d’or glimmered on her loosened hair.  A confused sense that the passing hour was the happiest in her life possessed her:  she looked down at the brace of wet yellow trout on the bog-moss at her feet; she gazed out across the crinkled pool where the Yankee Laird of Isla waded, casting a big tinselled fly for the accidental but inevitable sea-trout always encountered in Isla during the season—­always surprising and exciting the angler with emotion forever new.

Over his shoulder he was saying to her:  “Sea-trout and grilse don’t belong to Isla, but they come occasionally, Lady Yellow-hair.”

“Like you and I, Kay—­we don’t belong here but we come.”

“Where the McKay is, the Key of the World lies hidden in his sporran,” he laughed back at her over his shoulder where the clan plaid fluttered above the cairngorm.

“Oh, the modesty of this young man!  Wherever he takes off his cap he is at home!” she cried.

He only laughed, and she saw the slim line curl, glisten, loop and unroll in the long back cast, re-loop, and straighten out over Isla like a silver spider’s floating strand.  Then silver leaped to meet silver as the “Doctor” touched water; one keen scream of the reel cut the sunny silence; the rod bent like a bow, staggered in his hand, swept to the surface in a deeper bow, quivered under the tremendous rush of the great fish.

Miss Erith watched the battle from an angle not that of an angler.  Her hazel eyes followed McKay where he manoeuvred in midstream with rod and gaff—­happily aware of the grace in every unconscious movement of his handsome lean body—­the steady, keen poise of head and shoulders, the deft and powerful play of his clean-cut, brown hands.

It came into her mind that he’d look like that on the firing-line some day when his Government was ready to release him from his obscure and terrible mission—­the Government that was sending him where such men as he usually perish unobserved, unhonoured, repudiated even by those who send them to accomplish what only the most brave and unselfish dare undertake.

A little cloud cast a momentary shadow across Isla.  The sea-trout died then, a quivering limber, metallic shape glittering on the ripples.