The official Dual Destinies site has been updated, bringing with it a profile for Klavier and info on case three, Turnabout Academy!
Turnabout Academy takes place at Juniper’s school, the Themis Law School. Athena goes to visit her, but when a dead body turns up, Juniper is arrested by Fulbright on suspicion of murder. It’s up to Athena and the others to clear her name. Note that while the site doesn’t explicitly say you play as Athena for this case, the investigation screens are from her perspective, and you can see her thoughts in one shot, which is pretty indicative.
In addition, Apollo and Klavier (voiced by Toshiyuki Kusuda, who voiced him in the GS4 promos) take part in some sort of mock trial put on by Athena. How this is connected to the actual murder case is still unclear.
The Perceive system is also re-introduced, now as an investigation technique. With no Simon and Gin around to stop him, Apollo is able to use his bracelet to find a witness’ tell and draw out new information.