Jennifer Connelly plays a frightened young mother in the psychological thriller Dark Water. But this real-life young mother and her six-year-old son found different kinds of thrills in the parks and museums (and hospitals) of London.

It's the hour of night when telemarketers,­ not Oscar winners, are usually calling me. But these days, Jennifer Connelly is as much mother as movie star, and she's just put her two-year-old son to bed.

"Hi, is this Mark?" she asks. "I'm sorry to be so late calling you, but he was fighting me and fighting me."

"He," of course, is her son, and how the boy came to be born in London was an adventure of sorts, set in the Royal City and starring Jennifer Connelly in a way much different than you'd expect.

When Connelly left her longtime hometown of Brooklyn to move to London for three months in the summer of 2003, she was six months pregnant, arriving not to star in a movie but to support her husband, the British actor Paul Bettany, who was filming Wimbledon at the mother church of international tennis outside of the city. Along with her six-year-old son, Kai, they rented a house in Notting Hill Gate and settled in for the shoot, the culmination of which produced not only a movie, but also their newborn son.

"Paul had some days off, but he worked almost every day, first thing in the morning until evening," Connelly says. So she was left with her precocious six-year-old "and my massive belly."

That's when the adventures began.

Next month, Connelly plays a young mother in Dark Water, an edgy psychological thriller in which her big eyes widen over all manner of horror in a very strange apartment. But she didn't have time to be spooked by her London digs. She was rarely there.

"I think London is such a great city with kids," she says. "There's so much to do! You could do a whole kids' issue."

Most every morning, Paul was out the door, leaving Connelly and Kai with an extraordinary city to explore. If they were feeling lazy, which they rarely were, they only needed to cross a few streets and they were in the Princess Diana Memorial Playground. "Fantastic," she says. "It's in Hyde Park, sort of up by Kensington Palace. It has this massive pirate ship that's sort of plunked down in the middle of this sand pit. The whole thing is beautifully landscaped. There are these little wooden boats and climbing structures and plants and big musical instruments that the kids can play on. It's really kind of magical."