In-N-Out Burger heiress Lynsi Snyder says she'll reveal the 'whole truth' of the fast-food dynasty in an upcoming book

• In-N-Out owner Lynsi Snyder has penned a book titled "The Ins-N-Outs of In-N-Out Burger."
• The billionaire says she plans to reveal 75 years of history in the book, set to be released in October.

No other restaurant chain keeps its closely held secrets under wraps more than In-N-Out Burger.

But that might soon change. Lynsi Snyder, the billionaire owner of the Southern California burger institution, has written a book that promises a revealing look at the 75-year-old family business. She plans to "share the whole truth" about the business through interviews with "several retired In-N-Out family members," Snyder wrote on her Instagram page.

"I have waited so long to tell the true In-N-Out Story," Snyder wrote on Instagram, where she has more than 53,000 followers

The book, titled "The Ins-N-Outs of In-N-Out Burger: The Inside Story of California's First Drive-Through and How it Became a Beloved Cultural Icon," is set to be released October 17, according to Amazon, where pre-orders are available.

"I collaborated with several retired In-N-Out family members to share stories that happened during the 75 years of our special company," Snyder wrote on Instagram. "It's been an amazing experience to pull these memories. I want my family to be honored but also share the whole truth. I can't wait to share this book with you and hope you enjoy it as much as I have enjoyed putting it together!"

In-N-Out has remained a privately run family business since Harry and Esther Snyder founded the company in Southern California in 1948.

Lynsi Snyder, 41, inherited control of the family business in 2017 and became one of the youngest billionaires in the US. Her rise to the top of the chain at such a young age was largely the result of the untimely deaths of several of her family members, including her father, Guy Snyder, and her uncle, Rich Snyder. They were the only children of Harry and Esther Snyder.

Lynsi Snyder has expanded the chain to Texas, Oregon, and Colorado since becoming In-N-Out's president in 2010. The company plans to expand to Idaho and Tennessee next.

The book release comes around the same time the chain plans to mark its 75th anniversary with a bash at the In-N-Out Burger Pomona Dragstrip east of Los Angeles. The October 22 event is expected to feature drag racing and live music. One of the headlining bands is .48 Special, the In-N-Out band featuring Snyder and her husband, Sean Ellingson.

Are you an In-N-Out insider with insight to share? Got a tip? Contact this reporter via email at nluna@insider.com or text me at 714-269-8873.