"Working with Martin on 'Sherlock' is really quite inspiring, 'cause he's so good at his job. And he and [Benedict Cumberbatch] have this fantastic chemistry," says the English actress.
"Coming into 'Sherlock' you have to up your game, 'cause they're so good together."
Abbington was recently photographed on set in a wedding dress, so it is all but officially confirmed that she's set to play Morstan. However, Abbington is reportedly sworn to secrecy until the season actually airs.
Freeman and Abbington met in 2000 on the set of "Men Only." And while the pair have two children, they have yet to marry.
"I'm an only child, I'm quite self-sufficient. I can get on with stuff on my own. I don't like to worry other people, either," admits Abbington.
The "Mr. Selfridge" actress recently famously had run-ins with cancer and bankrupcy, but refused to get help from Freeman.