Emma Stone on being haunted by her late grandfather & working with Colin Firth

She's one of Hollywood's most charming, witty and sarcastic stars. He's one of Britain's most charming, witty and distinguished actors. So how did Emma Stone and Colin Firth get on during an intense two months together in France on set of their new film Magic in the Moonlight?

Appearing on The Letterman Show to promote the Woody Allen-directed rom-com, Stone was asked how she felt about her famous co-star.

"He's tricked us all into believing he's this charming, lovely fellow - he's a nightmare," the Superbad star joked.

"He's a toolbag," she deadpanned.

The 25-year-old actress plays a spiritualist helping a rich family in the 1920s-set film, while Firth's character is tasked with exposing her as a fraud.

Suggesting that she was well-placed in her spiritual role, the Superbad star also revealed that she is being "haunted" by the ghost of her late grandfather - who she says leaves quarters (15 pence coins) lying around for her to find.

"That's the joy of it; it's not a logical thing," she said. "It's magical. Like ectoplasm."

Emma Stone and co-star Colin Firth with Woody Allen on set of Magic in the Moonlight