Polly's Pearls is set in the small, idyllic town of Ryant River and follows Samantha White, a retired teacher who owns and operates the Drippity Do Dah coffee shop out of her home. Samantha runs the business with her business partner, Larry Lumkey, and friend and cleaning lady Lucy Deerfoot.

Samantha lives with her mixed-breed dog Abby, who is part Chihuahua and somewhat psychic. The cafe is a dog-friendly community hub with eclectic decor, outdoor seating, and regular gatherings like the Coffee Cup Gamers group.

Sam and her best friend, Nedda Braake, are enjoying a morning coffee while observing the family of recently deceased local resident Polly Parker, who passed away unexpectedly. Initially assumed to be natural causes, her death turns suspicious when town sheriff Hudson MacKay arrests a mysterious park ranger named Alexander DuPree at the cafe, accusing him of Polly's murder. Town handyman Ferguson later reveals Alexander to be Polly's stepson.

The mystery develops further around Polly's murder when Polly's very valuable pearls go missing. The pearls are bequeathed to Polly's daughter, and the whole family is now questioning who took them and why. Samantha learns vital information from coffee shop customers who visit the Drippity to gossip and sip coffees. Abby, the chihuahua, assists with the help of her four black whiskers' intuitive role in uncovering clues.