The mystery is gone. All that's left is a free car.
The unexplained appearance of a large -- some might say "car-sized" -- Amazon.com delivery locker at Justin Herman Plaza on Thursday mystified spectators and sparked speculation, egged on by the online retailer's initial refusal to divulge the giant locker's purpose.
Turns out the storage locker contains a new Nissan Rogue, the centerpiece of a marketing stunt organized by the online retailer and automaker Nissan.
Beginning at about 10 a.m. Friday, anyone willing to make a post to social media with the right hashtag could receive a code to use to try to unlock the locker.
Most codes unlocked a voucher for a free MP3, but there are also Kindle Fire tablets and Kindle televisions to be had -- as well as the car, Amazon spokeswoman Kristin Mariani said.
"Someone's going to get a car today," she confirmed.
As of about lunchtime Friday, the car was still on offer, with a film crew retained by Nissan filming contestants' efforts for a future commercial.
Hopefuls included office workers, tourists walking from the Ferry Building, and a collection of street kids who'd spent the night nearby on Mission Street.
Ray Torres and Makayla Herlihy were some of the first in line before the fun began at 10 a.m.
"We saw it last night, but no one would tell us what was inside [Thursday]," said Torres, showing the MP3 voucher he'd just won.