What to make of “Cold Case Hammarskjold,” Mads Brugger’s idiosyncratic odyssey into the vile heart of African colonialism and the conspiracy theories surrounding it to this day?

“Art as Ecosystem 1,” the first of two talks at Guild Hall moderated by the artist Eric Fischl, will bring together art world luminaries to take the measure of the discipline’s health and vitality. The venue will also present a doo-wop concert, and the American Modern Opera Company.

Amagansett’s Upstairs Art Fair, a small but well attended fair attracting innovative dealers from the East End and New York City, will return for its third iteration this weekend at its home on the top floor at the old Amagansett Applied Arts building at 11 Indian Wells Road.

A whale that was entangled in fishing net in the waters off Town Line Beach in Sagaponack has freed itself, Southampton Town police said Monday evening.