When to Watch: Tuesday, may 21 at 9 p.m.What to Expect: The Grim Reaper is coming to Grimm! You're welcome. When we chatted with David Guintoll, Silas Weir Mitchell and Bree Turner recently, they revealed that one of the three of them might not make it out of the finale alive. And you know what makes us really nervous? The fact that the episode title is: "Goodnight, Sweet Grimm." Yikes.