OTTAWA — Early Monday evening, a special container, about five to six square feet, was unloaded from an airplane at Toronto’s international airport. Inside it was more than 20 million Canadian dollars, about $14.8 million, in gold and other valuables. It was swiftly moved into a secure cargo holding facility. Then, like many a suitcase, it vanished. Announcing the theft on Thursday, Inspector Stephen Duivesteyn of the Peel Regional Police, the force that patrols Toronto Pearson Airport, offered few details about how the high-value container had disappeared beyond perhaps the obvious: by “illegal means.” The investigators gave so little information...