Robert Sheehan, David Tennant star in new horror film 'Bad Samaritan'

LOS ANGELES (KABC) -- There's a creepy movie now in theatres that may make you think twice the next time you park your car with a valet. It's called "Bad Samaritan."

In the film, a couple of valet parkers, with the help of GPS, sometimes drive customers' cars back to their homes to rob them while they eat.

They decide to rip off a particular nasty customer and discover something shocking.

Instead of rescuing her immediately, the thief vows to be back, but things get complicated.

Robert Sheehan and David Tennant both have done Shakespeare...So, to do a horror film -- movie's villain considered it a killer opportunity.

"He's a monster, without a doubt," said Tennant. "And I can't pretend it's not quite fun to dabble in those waters."

"They'll experience a movie that's very much couched in reality," said Sheehan. "And I think that's why it's so legitimately scary."

And it may make people think twice about leaving their garage door openers in the car when they valet park.

"Bad Samaritan" is rated R, in part for its violence. So, hang on for the ride!