Unbelievable’s unbelievably good. Believe me.

Imagine an eighteen-year old woman, in foster care since she was three, at last able to move into a half-way house, semi-independent but with staff on-site to protect and support her. And then she’s raped. In her room. By a masked intruder, who comes in through the window from the balcony, binds her, assaults her, takes pictures and goes a few minutes after first appearing.

Kaitlyn Dever as Marie Adler

An appalling, devastating experience. But it gets far worse. After showering sympathy on the victim, Marie Sadler, played with great empathy by Kaitlyn Dever, individuals start to doubt her story. Worse still, the doubts eventually reach the (male) detectives investigating the case. Ultimately, far from having the police on her side, hunting down a criminal, she finds herself facing charges herself, of having made a false report.

It’s a powerful and immediately gripping start to a remarkable Netflix original mini-series, of just eight episodes, called Unbelievable.

All the better for being based on a real case.

Or rather, real cases. Because in episode 2, we’re taken forward three years to 2011, and from the state of Washington into Colorado. There Karen Duvall, a detective excellently portrayed by Merritt Wever, has been called in to investigate an appalling rape. The masked rapist came in through a window, bound and assaulted his victim, took photos and left. There are some key differences: he took four hours with this victim, and he made her shower for twenty minutes, to wash away all trace of DNA. But these are enhancements in his technique. The basic crime is the same.

A stroke of luck reveals to the detective that a similar offence took place in another nearby police district. In fact, when she contacts the detective investigating that case, Grace Rasmussen, played in another fine performance by Toni Colette, the two women quickly realise that this rapist knows something of police procedure, and never commits a crime in the same district twice, relying on lack of communication between separate stations.

Merritt Wever as Karen Duvall and Toni Colette as Grace Rasmussen

So they combine their investigations and discover that there are several other crimes to add to the two they already know about. These were, in reality, what came to be known as the Washington and Colorado serial rape cases.

From this point on, the series is following two stories: that of Marie Sadler in Washington, and that of the two detectives in Colorado. Both story lines are gripping from the outset, intense in their impact on the viewer, powerful in their suspense. We suspect that the lines must eventually intersect, but we can’t be sure and we don’t know how or when. The best kind of crime TV.

The basis in fact gives the series poignancy and impact. The writers have changed names and naturally to some extent fictionalised the account, but the key events are as they were in history. Add to that excellent writing and superlative performances, above all by the three main actors, and you have in Unbelievable an outstanding series it would be a pity to miss.