“Hold it right there, pal,” Young said. “I have already been over those cases with a giant magnifying glass, and there is nothing there that would help us make a case against the twins.”

“Oh.”

“Except, maybe, one thing.”

“Ah. Which one?”

“Let’s call it the Nantucket file, for want of a better name.”

“What does Nantucket have to do with this?”

“It has to do with the twins’ alibi for the last of the rape/homicides.”

“What was their alibi?”

“They said they were on board a yacht that they had raced to Nantucket and were delivering to Boston.”

“Did that check out?”

“At first. I had a local Nantucket cop, Lieutenant Jake Potter, run it down for me. He found the owner of the yacht, which is named Hotshot, on somebody else’s yacht in the marina. When Jake spoke to him, he said that the twins had left Nantucket to deliver Hotshot to Boston, and the murder had occurred during the time when Hotshot would have been at sea. There would have been no way they could have gotten to Islesboro during that time, so their alibi was airtight.”

“That’s discouraging.”

“That alibi was all that I knew at the time, but when I went through the files last week, there was an addendum to the file that I hadn’t seen before.”

“What did the addendum say?”

“It said that, after Jake had sent me the file, he had gotten a call from a kid he had wanted to interview but couldn’t find. The kid delivered groceries to yachts in the marina. He had arrived aboard Hotshot as they were ready to cast off. He had handed the groceries aboard, got paid, and helped them stow everything below. It was a choppy day, and they didn’t want loose cans of tomatoes flying around the cabin.”

“So how does this relate to the twins’ alibi?”

“According to this kid, there were four people aboard, and none of them were twins. He cast off their last line and watched them head out of the harbor.”

“So they lied about their alibi?”

“Right, and the owner of Hotshot backed their lie, saying that the twins had sailed on her.”

“Is that enough to charge them?”

“Wait, there’s more.”

“Tell me.”

“Jake Potter checked the local airport to see if they could have left the island on a plane or chopper, and he learned that a small airplane left before Hotshot sailed.”

“What kind of airplane?”

“A light, high-winged airplane. That’s got to be a Cessna, but Cessna has several high-winged airplanes, and there are other manufacturers, too.”

“Did Potter get a tail number?”

“No, they didn’t buy fuel, so there was no record of a tail number.”

“Anything else to add?”

“No, it’s just clear evidence that they didn’t sail aboard Hotshot, and that they could have left the island by airplane.”