Time Traveler

I try to enter the building but a marine stops me and demands identification. I tell him I am an American cryptographer. He can tell from my accent that I am telling the truth about being American and figures I couldn't be on the base unless I was authorized. He allows me entry. I know I am here under false pretenses. I look around and see one corner of the building has a sign indicating it is Signals Branch. I figure that's a logical place for a cryptographer to go, so I go there. I see a radioman with a headset listening to Morse Code. He is copying the text out in letters on a pad. I look at it over his shoulder. It reads:

KX WZ SL OU TL NP ZW WG EW PM HQ ZQ ZD HZ LE QN TL TG FY NE WM OF NE FP TG SG TL MQ FN EL RY PA EL PZ RF ED DW BG WU NU ZW BT AH WE PM PS NT CS NY GQ AO QS QL WF DN FZ PY GN HW RY

He notices me for the first time. "We don't get many civilians here," he says. "What's your story, Mac?"

"I'm a cryptographer. I think I may have been sent here by mistake. If you can get someone to escort me off the base, I'll leave."

"No, don't leave. You're just what we need right now. I just got this message. I recognize the hand. Morse operators all have a unique cadence and style. It's like handwriting. This one is from one of the coastwatchers. Someone needs to decrypt this. It could be important."