You're a maximum-security prison warden who has just heard there's a riot in C Block. Two guards have been killed and a murderer is holding four more hostage.

Say Cheese.

This is just one of the directions photographer Howard Schatz fired at his subjects for his new book, "In Character: Actors Acting" (Bulfinch, $50), in which 100 stars of stage and screen are shown in close-ups instantly morphing into various roles.

Feigning the prison guard, the deadpan Fred Willard ("Best in Show," "Anchorman: The Legend of Ron Burgundy") rubs his temple and stares with tired menace. In the next photo, he smiles tightly with anticipation. Now, he's an eager real estate agent watching a buyer sign a bloated contract.

Likewise, Don Cheadle is a crestfallen stockbroker; Danny Glover, a jubilant basketball coach; Hal Holbrook, a Baptist preacher; and Edie Falco, a gloating little sister.

Schatz sat each actor down — most without makeup — to shoot him or her in the moment-to-moment manifestations of the craft. He also gleaned each actor's thoughts on acting and individual method, which for some was quite consuming.

"They let themselves be bare before me," says Schatz. "They screamed and yelled and cried and moaned and sobbed and growled. I gave them a scene, a character and maybe a line and, boom, all of sudden there was another human being in front of me."

Drawn to the composition of the human body, Schatz photographed more than 100 athletes in various poses and contortions for the book "Athlete." His other books include "Botanica" and "Rare Creatures: Portraits of Models."

Accustomed to directing models, Schatz had limited experience with actors but always liked their creative process — "They make it look easy; it's really hard," he says.

"In Character" has received good reviews. Film critic Roger Ebert writes in the foreword: "To journey through the book and see familiar faces was to realize how much, during a career of looking at movies, I have come to love actors, to appreciate the gifts they bring."

But is it really more than just making funny faces?

"I think it's a developed skill," answers Schatz. "I think they've learned how to use their body and face — they call it an instrument — to say what they want to say, to project the character they want to project."

For Christopher Lloyd, it's a mysterious process. In the book, Lloyd, who is most famous for inventing the flux capacitor as Doc Brown in the "Back to the Future" movies but has acted in dozens of plays, becomes a violin teacher hearing his prized pupil massacre Mozart.

"I really don't know what my face is going to look like on screen, how my expression registers," Lloyd says. "I just try to really get into the moment and make that believable. And what happens, happens — and very often what happens is something very different or surprising for myself."

Veteran comedian Robert Klein immediately launched into improvising lines for his characters. (A video of his photo shoot is at www.howardschatz.com.)His photographed roles include a little boy refusing to eat his broccoli.

"If I'm going to be a 5-year-old child, there's no holding me back," says Klein, defending his performance.

The actor describes his face as "rubbery," which when photographed up close without makeup, "looks like the map of Vermont." For a character of the same boy glaring at his older sister as she happily eats the vegetable, Klein curled his lip like his father would when he was mad.

But Klein doesn't adhere to any method acting techniques.

"Acting is pretending you're someone else for a while, then you go out and have lunch," he says simply.

In the book, Willard supplies another acting platitude: "I love acting because when it's time to speak, everyone else has to shut up before your cue."

Willard is perhaps best known as one of the main players in Christopher Guest's movies, which aside from "Best in Show," includes "Waiting for Guffman," "A Mighty Wind" and the upcoming "For Your Consideration." In the photo shoot, he sported blond hair, dyed for the new movie.

His source, he says, often comes from his two years in the Army and a subsequent job in a credit office.