Martha Stewart abruptly canceled her book signing in New York after getting interrupted by an anti-fur activist ... and it's clear the demonstration ruffled her feathers.
We've just obtained video from Martha's book signing at the Macy's in NYC's Herald Square Wednesday night, and it's wild ... you see the demonstrator come charging at Martha, holding up a sign about killing animals, ranting about Canada Goose and Martha having "blood on their hands," as security guards quickly haul her away.
Martha's clearly freaked out by the whole thing ... we're told the signing was called off shortly after the incident.
It's unclear why the activist targeted this event ... as best we can tell, Martha doesn't have any connection to Canada Goose.
By the way, tons of fans had flocked to the event to snag a copy of her new book, "The Martha Manual: How to do (Almost) Everything!" Looks like they're going home empty-handed.