Source: TV Guide [follow link for companion article]
GRIMM - TV GUIDE VIDEO: 'BIG FEET' SNEAK PEEK # 4 - AIRS FRIDAY, MAY 11, 2012 AT 9/8C ON NBC
A double homicide brings Nick (David Giuntoli) into contact with a creature friend of Monroe's (Silas Weir Mitchell) who is suffering from a condition that prevents him from completely reverting back to human form. Also: Hank (Russell Hornsby) sees something that's seemingly inexplicable.
Guest stars include Kenneth Mitchell, Roger Bart, Andy Gates and Jessica Martin.