 Eight-year-old Mac has outgrown his imaginary friend, says his mother, so he takes his buddy Bloo (a walking, talking security blanket) to Foster s Home for Imaginary Friends. Here all sorts of odd characters, given up by their creators, are welcome to stay until new kids come to adopt them. Mac strikes a deal with Madame Foster, the proprietor: as long as he comes to visit every day, Bloo will not be put up for adoption.