McMahon was the first mate to Captain Hanso.
At some point after the Mage Clan Wars, McMahon and co. sailed north-east from Kingsport on a mining expedition. He made a log of his experiences. From the outset, he was disgruntled, as while he'd expected the position of first mate to be exciting, all he did initially was watch the deckhands argue. To make matters worse, he became seasick, but repeatedly refused Hanso's offers of ale to alleviate his symptoms.
At some point, the ship was caught in a storm. After being battered for three days, a tidal wave carried them inland into Kehjistan, stranding them in the desert. Hanso disappeared soon after landfall, and the surviving crewmembers were convinced that some sort of monster was after them. McMahon wondered if the survivors were the unlucky ones.
The crew's fears turned out to be accurate, and the creatures attacked the wreck while the crew was sleeping. McMahon managed to get away, but he doubted he would last long. He could hear the creatures in the shadows...giggling...