Nicolas Cage's movie shoot was interrupted when a desperate parent got onto the closed set, and asked the movie star to help find his missing child.
Nic was shooting "Dog Eat Dog" near Cleveland on Wednesday ... when Britt Ramsey, stepfather of 15-year-old Alexis Boroviak, approached him. Alexis disappeared 11 days ago, and Britt asked Nicolas to take a pic with her "missing" poster ... knowing it would shine a spotlight on her case.
Britt tells TMZ he had to sneak onto the set, with the help of a community leader, but he's positive it was worth the risk ... to get the word out about Alexis.
He says Nic offered condolences, and was happy to do anything he could to help.