The Tunnel of Doom - The Mac 'n' Ivy Mysteries, #5

Is Mac the next hot new movie star? Probably not. But he is an extra in a movie being filmed near a mysterious California mountain famed for the myths and legends surrounding it. He even gets a promotion above "extra" level; now he's lumbering around head-butting other actors as Bigfoot. Ivy is mildly indignant that she's a movie-extra reject. Too short. Although her job as assistant to the ranch woman providing lunches for cast and crew does not, at least, require a costume both hairy and itchy. Production of "The Tunnel of Doom" does not go smoothly.
A flash-bang explosion. A dead bus. A poisoned salad. Someone is definitely determined to keep the movie from being completed. And when the sabotage escalates to a murderous level, Ivy and Mac are right in the middle of it.