A frozen road trip. Relentless secret agents. And a Jack Russell Terrier who just drank from the Holy Grail.

Lost for centuries, an ancient cup possessing divine grace was hidden away to protect it from a shadowy power known as the Organization. The silence breaks in the winter of 1961 when Mark's best friend—a Jack Russell Terrier named Mrs. Henry—takes a sip from a stranger's battered cup during a freezing day out on the ice.

Now armed with terrifying and unpredictable supernatural powers, Mrs. Henry and Mark are thrust into a high-stakes cat-and-mouse game. Their only hope of escape? An erratic, guitar-slinging musician from Minnesota named Bob - who just might be destined to change music history - and a grueling vintage car chase from the frozen streets of the Midwest to a snowy sanctuary in northern Wisconsin.

But Mrs. Henry's new abilities are growing, and time is running out.

As the roads get slicker, the agents get closer, and the stakes get higher, Mark and Bob must keep the cup safe... or risk losing it forever.

Buckle up for a fast-paced 1960s adventure packed with humor, heart, blues-fueled detours, and a dog who takes absolutely no nonsense.