As Nick (David Giuntoli) and Hank (Russell Hornsby) turn their attention to a string of attacks where victims are left without their memories; Nick weighs whether or not he should regain his Grimm abilities. Trubel (guest star Jacqueline Toboni) joins the investigation and puts herself in harm's way. In Vienna; Adalind (Claire Coffee) is being held captive and learns that she is more connected than ever to Nick. Meanwhile; Captain Renard (Sasha Roiz) continues to fight for his life as a mysterious visitor (guest star Louise Lombard) arrives to help him. Bitsie Tulloch; Silas Weir Mitchell; Reggie Lee and Bree Turner also star. Phillip Anthony Rodriguez and Brian Letscher also guest star.