‘The Boy' starts slow, falls short

A creepy doll and a creepy house are the main ingredients of “The Boy,” a small-cast horror movie that spends a lot of time building itself into a psychological thriller, only to veer in a more literal direction at the end.

It still has enough scary moments to satisfy horror fans, but you’re left wondering whether it might have been more disturbing had it stayed on its original path.

Lauren Cohan, of “The Walking Dead,” plays Greta, an American who escapes a bad relationship by traveling to England for a job as a nanny to the son of an older couple (Jim Norton and Diana Hardcastle). Only when she arrives at their creaky, sprawling mansion does she learn that the lad, Brahms, is actually a porcelain doll, a surrogate for their son, who is said to have died years earlier in a fire.

“Whatever it might look like on the outside,” the father tells her, “our son is here. He is very much with us.”

The parents quickly bolt - they desperately need a vacation, they tell Greta - leaving her with Brahms and a detailed list of how to care for him. Alone in the giant house, except for an occasional visit from Malcolm (Rupert Evans), who delivers groceries, Greta undergoes a transition from thinking that the couple are bonkers to suspecting that the doll is indeed somehow alive.

It’s a classic descent-into-madness setup, and Cohan does a reasonable job with what she’s given. (William Brent Bell directed the script, by Stacey Menear.) There was room to give her more - the first hour of the film is a bit sluggish - and Cohan never really gets to finish her exploration of whether Greta has lost her mind because the film takes an abrupt turn.

It’s one of those twist endings that, though surprising, also feels like a letdown.