Entertainment

The lamest show on earth!

Usually, you have to wait for the end-of-the-year awards season to see an elaborate period piece that fails as spectacularly as “Water for Elephants.”

This clunky, plodding, romantic circus melodrama showcases the improbable, less-than-scintillating triangle of Reese Witherspoon, Robert Pattinson and Christoph Waltz.

My heart began to sink with the contemporary prologue, when an old man named Jacob (Hal Holbrook) launches into a gloomy series of flashbacks beginning with the death of his Polish-born parents in a 1931 car crash.

Left penniless and now played by a sulking Pattinson, Jacob drops out of his veterinary studies at Cornell and, for no apparent reason, hops a circus train.

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After a brief stint shoveling manure, Jacob is named staff veterinarian by August (Waltz), the sadistic, desperate owner of the struggling circus.

Ordered by his boss to tend to a seriously ailing horse that August’s wife Marlena (Witherspoon) rides bareback on, Jacob euthanizes the animal instead.

Though August is given to expressing his displeasure — and saving money — by frequently having staff members tossed off moving trains, he instead assigns Jacob to a new star attraction he’s acquired, a performing elephant named Rosie.

August nearly kills Rosie in a rage after she throws Marlena.

But our hero discovers the big animal responds just fine to his kindness — and commands in Polish.

Meanwhile, Marlena and Jacob are batting their eyelashes at each other, and August is beginning to get suspicious, particularly after Jacob rescues his wife during a speakeasy raid.

Richard LaGravenese’s wobbly adaptation of Sara Gruen’s novel lumbers along even more slowly than the elephant, and is full of stilted dialogue — not to mention such weary stereotypes as dying old-timers and helpful midgets.

While there’s some nice train footage and incidental color, director Francis Lawrence (“I Am Legend”) achieves at best a shaky sense of time and place — New York State during the Great Depression. Overall, it makes sleazy circus world look way too pretty.

The anti-climactic climax, a big-top disaster, is so confusingly staged and edited that it’s hard to figure out exactly what’s going on.

Some of this could be more easily overlooked if the stars any semblance of romantic chemistry, which they don’t.

A miscast Witherspoon seems equally uncomfortable as a femme fatale or as a circus performer.

Pattinson of the “Twilight” movies never manages to suggest Jacob has any kind of inner life — the elephant is more expressive. Pattinson’s scenes with Witherspoon have no heat whatsoever.

Waltz, so entertaining in “Inglourious Basterds,” has been encouraged to ham it up mercilessly as the heavy.

But he never conveys any serious sense of menace.

“Water For Elephants” is less fun than any circus movie I’ve ever seen — and I’ve seen lots. Maybe they should send in the clowns.

lou.lumenick@nypost.com