It's the latest release from horror specialist Blumhouse, recent films from which have included Five Nights at Freddy's and M3GAN. They're horror films that aren't too scary, the sort of thing teenagers might go see to get out of the house or watch at a slumber party. Blumhouse releases tend to be decently acted, professionally made, entertaining time killers but nothing terribly scary or memorable. Imaginary ticks all those boxes.

Jessica (DeWanda Wise from Netflix's She's Gotta Have It) is a successful writer and illustrator of children's books and loves her musician husband Max (Tom Payne from The Walking Dead). But although she seems to get along fine with her younger stepdaughter Alice (Pyper Braun), things aren't going so well with Alice's teenage sister Taylor (Taegen Burns), who resents Jessica.

Jessica is prone to terrifying nightmares and Max suggests they go live in her "happy place", the home in which she lived with her parents as a child, to see if that helps.

At first, the move seems to be good for Jessica. We get some idea of what might account for Jessica's trauma: her mother died when she was young, her father had a breakdown and now lives in an assisted care facility and at the age of five, she was sent to live with her grandparents.

But that's the stuff of drama if not soap opera, not horror, so we know there's more to it than that.

A couple of neighbours pop up - teenager Liam (Matthew Sato) who catches Taylor's eye but could be a bad influence, and older lady Gloria (veteran Broadway musical theatre star Betty Buckley). She used to babysit Jessica who can't remember that, but then she was very young at the time. At first it seems like Gloria is there simply as Ms Exposition, but she turns out to be more important than that.

Max is soon called away to go on tour and Jessica, who works at home, assures him everything will be all right.

Which, of course, means it won't be.

The ongoing tensions with Taylor are unpleasant but it turns out to be sweet little Alice who'll be the major cause for concern. She's drawn to the basement where she finds a teddy bear hidden away and brings it upstairs, naming it Chauncey.

Soon she's having long, animated conversations with Chauncey as well as tea parties and other games and requesting extra food for him. Jessica thinks it's sweet: doesn't every kid have an imaginary friend at some stage? (Well, I didn't, but maybe I was abnormal).

Chauncey and Alice have a scavenger hunt but while it starts out innocently enough, some of the later items are destructive and potentially deadly. And things get even stranger from there.

Director Jeff Wadlow (Truth or Dare) wrote the script with Greg Erb and Jason Oremland and they deliver some effective jump scares and creepy moments and a decent twist or two along the way. There are a lot of practical effects here and they work quite well.

A stationary, normal-looking teddy bear isn't particularly scary to look at (unlike a clown doll, which can unnerve many) but Wadlow does a pretty good job of imbuing Chauncey with a sense of menace. Having the bear disappear between shots is an old, simple device but it can still work. And let's just say not all of Chauncey's appearances are cuddly.

Some of the complications in the latter, noisier part of the film feel excessive but Imaginary does what it sets out to do pretty well.

There are quite a few "scary teddy" B horror films. The Pit (1981) is a particularly weird one in which the bear isn't the whole focus: it's not for all tastes, but I recommend it to those who, like me, enjoy very strange films.