Highways and Thai Ways

When two inexperienced middle-aged backpackers board the plane with return tickets to Bangkok, a change of clothing, and accommodation booked for the first night (so they thought), they could never have imagined the adventures, wonders and thrills that await them.
Travelling by every means possible, and sleeping in some very strange places, they eat dinner cooked by an opium-smoking village chief, graze from roadside food carts, and forget all about sandwiches.
But who are Dr. Doom and Supa the Silent One, and what is the Myanmar banana? And why do the couple need an armed ex-monk for protection?