Charlotte Hamlin may be a grandma with pure-white hair, but no one who’s seen her in action would think to call her old. About to retire, she wonders how she can get people excited about healthful living. She’s 68 when the idea strikes to ride her bike solo across the U.S.

But that’s just the beginning of her dream. Next comes Europe, then Asia, Australia, and the Trans-Canada Highway. Before Hamlin hangs up her helmet she’ll cycle more than 12,000 miles around the globe and share her upbeat health message with thousands.

Her story is peppered with danger and miracles. She’s chased by bandits in Nepal and detained for unwittingly entering forbidden territory in China. She rides 50 to 80 miles a day through searing heat, pouring rain, and bone-chilling snow, along teeming freeways and tranquil mountain villages, where interesting folks embrace her with their hearts and homes.

Hamlin’s is an adventure of unswerving faith in her unfailing Guide. And a fascinating story that takes you along for the ride.