If you happened to bump into a man in a skull mask and a woman in a highwayman's hat in San Diego Comic-Con, you might have inadvertently walked into none other than Sherlock's Mark Gatiss and Amanda Abbington.
Yes, Mycroft and Mary Watson went incognito at the great fan get-together, and absolutely no one recognised them.
At one point, Abbington even took her sneaky shades off, and still nobody clocked her. Clearly no one at San Diego Comic-Con is quite as perceptive as Sherlock Holmes.
The good news is it left plenty of time for Gatiss to poke around all the Doctor Who and Sherlock merchandise, from Benedict Cumberbatch Bobbleheads to a replica Tardis.
He was less impressed by the Doctor Strange costume – but then, Hollywood blockbusters do have a habit of getting in the way of Sherlock filming...
Of course, Gatiss and Abbington aren't the first stars to take advantage of a little cosplay when visiting Comic-Cons. From Matt Smith's Bart Simpson to John Barrowman's Kylo Ren, there's nothing like a mask to let celebs join in the fun.
Clearly, Mary and Mycroft enjoyed their time out of the spotlight. Now, about that Sherlock series four air date...