Johnny Depp making cameo in girlfriend Amber Heard's movie

(UPI) -- Johnny Depp and Amber Heard were spotted sharing a romantic dinner in London last week, but it turns out the visit wasn't all play.

Depp, who is in town shooting Into the Woods and Mortdecai, will also be making a cameo in London Fields, which stars Heard opposite Billy Bob Thornton and Jim Sturgess.

London Fields is an adaptation of the 1989 noir murder mystery novel by Martin Amis, who adapted the screenplay with Robert Hanley. Heard stars as Nicola Six, who orchestrates her own murder to avoid aging.

Depp, 50, and Heard, 27, met on set while filming The Rum Diary in 2009, and rumors of their relationship surfaced after Depp split from his longtime partner, Vanessa Paradis, in 2012.