And readers thought that Rachel Watson, that girl on the train, was an unreliable narrator!

Paula Hawkins – whose debut thriller was the top-selling book in America for the past two years – has upped the ante in her good-but-not-great follow-up.

“Into the Water” is dripping with first- and third-person narration that cannot be trusted. While the heroine of “The Girl on the Train” had issues with alcoholism and blackouts, there are other reasons for literary deception in the new book.

Some of the characters are liars. Some have incomplete or willfully selective memories. Some are just crazy. All of these people have secrets.

The story is set in a small town called Beckford, a throwback riverside community in northern England. One particular bend in the river is a spot that has come to be known as the Drowning Pool. It is a place with a dark history, widely regarded as “a suicide spot.”

It also is ominously said to be “a place to get rid of troublesome women.”

This is how it has been in Beckford for centuries, as far back as 1679, when superstitious townfolk suspected young Libby Seeton of witchcraft, bound her and watched her sink in the water. The people living here now all know the old stories, but they don’t talk about them.

Then along comes Danielle Abbott, who grew up here, obsessed with the history of the Drowning Pool. Planning to write a book, she starts asking too many pointed questions, ruffles too many feathers, makes too many enemies. As they say in Beckford, she is a troublesome woman.

Perhaps inevitably, a 15-year-old girl – the best friend to Danielle’s just-as-troublesome daughter Lena – turns up dead, an apparent Drowning Pool suicide. The dead girl’s grieving mom blames Danielle.

Then, weeks later, Danielle herself dies suspiciously, her body pulled out of the very same water.

The woman’s estranged sister Jules, who nearly drowned here two decades earlier and is still deeply traumatized, wants to know why these tragedies keep happening. And a new police investigation, unlike the ones for previous deaths, is more than just a formality/cover-up.

Eventually, all of the secrets, past and present, like bodies in the Drowning Pool, will come to the surface: abusive relationships, illicit affairs, rapes, murders. Many of these crimes are interrelated – linked by one particular piece of evidence, a necklace, that changes hands more than a dog-eared library book.

The problem with “Into the Water” is that, while creepy from the get-go, it’s not the propulsive page turner that “The Girl on the Train” was.

It’s a slow starter. Glacially slow. Hawkins eventually gets it into gear, dropping bombshell after bombshell, chapter after chapter. But it takes her more than 200 pages to get to that point.

If the author didn’t have such stellar credentials – more than 20 million copies of “The Girl on the Train” sold worldwide – maybe her publisher would have insisted on revisions to a sluggish opening.

Most readers who have been eagerly awaiting her new book will probably have enough patience. But should they really have to wait?

It would be a much better book if, instead of dipping a tentative toe in the water, Hawkins had just jumped right into the deep end.