Not so mysterious is the Wine Train itself, which is best known for serving elegant multicourse spreads with expertly chosen wine while rolling through scenic vineyards. But since it started up in 1989, the journey has added winery stops, themed tours and special events like its latest offering. The train rolls from Napa’s McKinstry Street Station to St. Helena and back, with the 36-mile round trip running three hours for regular lunch and dinner trains and special tours running up to six hours. Turns out, serving a side dish of mayhem on the dinner train takes no extra time at all.

Desserts like blueberry lavender semifreddo might cap a meal.

Unveiled in May, the Murder Mystery event succeeds an earlier murder mystery dinner theater program conceived to give passengers reason to ride the dinner train when wineries were closed and the scenery cloaked in darkness. This year, according to Director of Food and Beverage Chaz Gallo, the operation was ready for a change, so it signed on with The Murder Mystery Company, veteran of numerous San Francisco restaurants, a couple of movies and many private and military venues. “The last (company) did more of a show,” Gallo says. “This one is much more of an experience, where guests become part of the show.”

It starts sedately enough, when actors, costumed for a stylish speakeasy circa 1915 (guests are encouraged to garb themselves accordingly) arrive at the station, along with everyone else. Soon diners are swept into a maelstrom of jealous lovers, vengeful Mafioso and undercover G-men. Participants not recruited to play suspects gather clues and work together to solve the whodunit.

“My favorite part is at the end of the night,” says Amber Lawson, the company’s Los Angeles director and one of the Wine Train’s lead actors. “I love seeing friends look at each other and say, ‘I didn’t know you could act!’” Murder Mystery events on select dates through November (dates subject to change), $256, 800.427.4124