The show is called "Romance on the Orient Express," not "Murder on the Orient Express," but like an Agatha Christie mystery, the viewer has some clues to put together.

"It's a modern story," said Cheryl Ladd, who plays a passenger on the Orient Express on NBC's Monday night movie at 9. Who shows up on the fabled train but a former boy friend. "It's very interesting," she said, "in terms of characters and the values of being 19, where the affair ended, and 10 years later when they meet again.

"You gradually put the pieces together and find out who they are," she said. "It's not all handed to the viewer on a silver platter. That appealed to me."

That and the location work. "My father was a Chicago-and-Northwestern engineer," she said. "But my train travel was quite limited." Actually, it was limited for this movie, too. The on-board scenes were done on a passenger car mockup. The real train appears only in the show's exterior shots.

Like the Express, Ladd these days is on something of a gentle roll. She and her husband have two daughters between them, his is 8 years old, hers is 10. Without the constant demand of a series, she said, "life is in much better balance."

But ah, the series days. Ladd replaced Farrah Fawcett in "Charlie's Angels" in 1977 and became a poster girl. Three million copies sold.

Now she says, "I try to chose roles that interest and challenge me." One of them, the part of a coal miner in "Kentucky Woman," sent Ladd into a Kentucky mine for two weeks -- "a real joy."

"Express" has a prettier look. "TV viewers are more sophisticated now," said Ladd. "What used to pass as Egypt on a back lot just won't fly anymore."