Jasper Hobson was sure the trading post he and his Hudson's Bay company expedition had built overlooking the Arctic Ocean was set on solid ground. On his maps it was shown as Cape Bathurst, but in fact it was a huge ice shelf, covered with earth and vegetation, and attached to the mainland by a narrow isthmus. In the dead of winter a volcanic eruption broke it loose and the spring thaw found the whole expedition--fourteen men, six women, and a baby--adrift on an ice island. If they drifted too far north they would become locked in the permanent icefield; westward, the current might carry through the Bering Strait and into the Pacific Ocean, where warm waters would soon melt their island from under them.