Set in early December The Third Medallion opens with Tyler and Lydia meeting Chandler Marr at a hotel bar in Bangkok, Thailand. Tyler and Chandler hit it off immediately, but Lydia is suspicious of him. Chandler starts showing up over and over again, which convinces Lydia that he's up to no good.
When a mysterious invitation arrives at their doorstep, Lydia suspects Chandler is behind it, but instead, it leads to Monte Carlo and a flamboyant Italian businessman named RP, who offers Tyler a multi-million-dollar contract to promote materials made from spider silk based on a new scientific breakthrough. Tyler accepts, and he and Lydia meet and befriend Dr. Viktor Palank, the scientist behind the breakthrough.
Following the celebration announcing the newly formed company, Viktor sends Lydia a commemorative medallion based on a conversation they had had at dinner. She discovers that the medallion is a replica Viktor created in his lab to protect his spider silk formula. Her curiosity aroused, to Tyler's chagrin, Lydia sets out on a quest to determine the true meaning of the medallion and who or what is behind the mystery surrounding it.
The Third Medallion is the first book in the Tyler West series.