Oscar-winner Kevin Costner returns to the director’s chair for the first time since Open Range in 2003 for this sweeping historical drama set during the first half of the 1860s against the backdrop of the Civil War.

“You just gotta keep going,” his weary horse trader growls towards the conclusion of this first chapter of a proposed four-part odyssey.

Horizon: An American Saga – Chapter 1 certainly does keep going, and going, trotting leisurely towards a three-hour running time to establish characters from gently intertwining storylines that leave hoof marks in Wyoming, Montana and Kansas.

Expect a little saddle soreness.

Surprisingly little happens aside from explosions of impeccably choreographed violence.

Performances are consistently strong and understated except for Jamie Campbell Bower’s unhinged son, who is several sleepers short of a railroad and brings intentional chaos to his scenes.

Chapter 1 whets appetites with beautifully crafted yet insubstantial morsels. Technical credits including production and costume design are top notch and evoke a savage, lawless era with aplomb.

The concluding minutes are reserved for a slick trailer for Chapter 2 to persuade us that the investment of three precious hours will reap rewards.

I’m not wholly convinced.