“You see,” Ralph Conyers explained, drawing back for a moment to look at the result of his labours, “this scheme, properly worked out, can keep a channel route such as the Folkestone to Boulogne one, for instance, perfectly safe.  Those black marks are floats, and the nets—­”

“One moment, Ralph,” Thomson interrupted from the background.

They all started and turned their heads.  Thomson drew a step nearer and his hand fell upon the paper.  There was a queer look in his face which Geraldine was beginning to recognise.

“Ralph, old fellow,” he said, “don’t think me too much of an interfering beggar, will you?  I don’t think even to your dearest friend, not to the girl you are going to marry, to me, or to your own mother, would I finish that little drawing and description, if I were you.”

They all stared at him.  Granet’s face was expressionless, the girls were bewildered, Ralph was frowning.

“Dash it all, Hugh,” he expostulated, “do have a little common sense.  Here’s a fellow like Granet, a keen soldier and one of the best, doing all he can for us on land but a bit worried about our submarine danger.  Why shouldn’t I try and reassure him, eh?—­let him see that we’ve a few little things up our sleeves?”

“That sounds all right, Ralph,” Thomson agreed, “but you’re departing from a principle, and I wouldn’t do it.  It isn’t a personal risk you’re running, or a personal secret you’re sharing with others.  It may sound absurd under the present circumstances, I know, but—­”

Granet laughed lightly.  His arm fell upon the young sailor’s shoulder.

“Perhaps Thomson’s right, Conyers,” he intervened.  “You keep your old scheme at the back of your head.  We’ll know all about it when the history of the war’s written.  There’s always the thousand to one chance, you know.  I might get brain fever in a German hospital and begin to babble.  Tear it up, old fellow.”

There was a moment’s silence.  Geraldine turned to Thomson.

“Hugh,” she protested, “don’t you think you’re carrying principle almost too far?  It’s so fearfully interesting for us when Ralph’s at sea, and we wait day by day for news from him, to understand a little what he’s doing.”

“I think you’re a horrid nuisance, Major Thomson,” Olive grumbled.  “We’d just reached the exciting part.”

“I am sorry,” Thomson said, “but I think, Ralph, you had better do what Captain Granet suggested.”

The young man shrugged his shoulders, his face was a little sulky.  He took the plan up and tore it into pieces.

“If you weren’t my prospective brother-in-law, you know, Thomson,” he exclaimed, “I should call your interference damned cheek!  After all, you know, you’re only a civilian, and you can’t be expected to understand these things.”

Thomson was silent for a moment.  He read in the others’ faces their sympathy with the young sailor’s complaint.  He moved towards the door.