On January 23rd, Big Finish Productions announced their latest project that will continue the story of the Doctor's beloved granddaughter. 

Susan's War will be a four part audio drama starring Carole Ann Ford in the title role, and William Russell who will reprise his role as first Doctor companion Ian Chesterton. 

Big Finish provided this summary as a peek into the story:

Gallifrey needs every Time Lord to fight the Time War. A summons has been issued across the universe to its prodigals. Whatever their skills, the war effort can use them.

Susan’s call-up papers have arrived, and, unlike her grandfather, she is willing to join her people’s battle and finally return home.

Because Susan knows the Daleks, and she will do her duty... 

From the title and summary of this new release, we can guess that the story will revolve heavily around the events of the infamous Time War and Susan's role in the conflict. Big Finish has also provided details that Susan will reunite with her grandfather, the Doctor, in his Eighth incarnation. We know that Susan has encountered this version of the Doctor several times, most notably in the audio adventures An Unearthly Child, Relative Dimensions, and Lucie Miller/ To the Death. 

Susan's War will release in April of this year.