STATEN ISLAND, N.Y. -- If you were wondering why Stapleton was more congested with traffic than usual today -- blame Marvel Comics.

In typically hush-hush Marvel fashion, the crew was mum on project details -- but sources close to the project confirmed the filming was for a Netflix series called "Group Therapy" -- i.e. the undercover filming title for "The Defenders."

On-set sources said the show will feature "all new faces" -- uh, unless you've been living under a rock for the past few years!

"The Defenders" -- a super-hero roundup of sorts -- stars Mike Coulter from "Luke Cage," Charlie Cox from "Daredevil," Finn Jones from "Iron Fist" and Krysten Ritter from "Jessica Jones."

Granted, none of the name "stars" were confirmed to be on S.I. -- but we overheard a crew member on set talking about a scene being filmed where "Luke gets punched and is down."

Filming went from Wednesday through Friday in a building on Union Place in Stapleton, with trailers and equipment trucks parked alongside both ends of Tappen Park.

Marvel's infatuation with Staten Island started in July and continued in September as Mariners Harbor and Snug Harbor provided the setting for "Iron Fist." Cast and crew were seen occupying a majority of Prospect Street, Union Place, Beach Street, Water Street and Canal Street.

Buena Vista Studios -- which owns Disney and Marvel -- chose this S.I. spot as a set because of the area's popularity, according to a source with knowledge of the project. The building they chose to film inside was listed by the Mayor's Office of Media and Entertainment.

So, Staten Islanders -- look out for your hometown on the forthcoming Netflix series. The show's premise is based on Marvel characters coming together to "save New York City."

"The Defenders" is set to premiere in 2017... sometime. A definitive date has yet to be announced.