We can’t say we weren’t warned. Boubs, the narrator of Rajiv Joseph’s new play, kicks off the show by informing the audience that “all of it is true. Or most of it, anyway.”

That “most of it” does a lot of work in “Dakar 2000,” which just opened at Manhattan Theater Club. But while ambiguity and uncertainty have long been great fertilizers for storytelling, Joseph’s two-hander about a couple of Americans in Senegal remains strangely uninvolving.