"Good evening, Chief Inspector. Pat Terne again?"
"Yes. We should have been on this one a long time ago, but the Royal Mail just handed over the evidence this afternoon."
"The Royal Mail?"
"It's diabolical, Sequence...there's no other word for it. Terne compromised one of the workers who handles the letters to Father Christmas."
"I know, Sequence. But we are going to need a Christmas miracle to crack this code. I hate how Terne telegraphs his moves, but we still keep missing him!"
"What do we have?"
"Eight letters to Father Christmas. We only found them because the accomplice was on holiday when the last one came in. A holiday he never came back from."
"How was the last one detected?"
"It arrived in the office on July 4. It's pretty unusual to receive letters to Father Christmas halfway through the year."
"Technically it's a bit more than halfway. July 4th was the 185th day of the..."
"Moving on...on top of that, it was from Turkey."
"And the others?"
"Found in the accomplice's desk, along with a notepad of scribbled sequences of numbers, mostly scratched out."
"What were the contents?"
"Nothing. Zip. Nil. The envelopes were all empty, even the last one we received. Just eight envelopes."
"Well, let me see the envelopes."
Sgt. Sequence looked over the envelopes for a few minutes, then returned to his desk and after a few minutes of searching the Internet, he returned.
"It's Terne alright sir, and this may be one of his boldest capers yet. Cancel the team's holidays...we're going to be busy foiling a robbery."
Based on the envelopes below that Sgt. Sequence inspected, can you determine where and when Terne plans to strike?