ABOARD U.S.S. PLYMOUTH Sail at 4 a.m., said Captain Jack Templeton of the U.S.S. Plymouth, laying down the long manila envelope marked Secret. Acknowledge by signal, he directed the ship's messenger, and then looked inquiringly about the wardroom table. Aye, aye, sir, said the first officer, Lieutenant Frank Chadwick. Ready at four, sir, said the engineer officer, Thomas; and left his dinner for a short trip to the engine room to push some belated repairs. Send a patrol ashore to round up the liberty party, continued Captain Templeton, this time addressing the junior watch officer. Tell them to be aboard at midnight instead of eight in the morning. Aye, aye, sir, said the junior watch officer, and departed in haste.