hi Sylvia,
I'm thinking this could be pretty engaging. If you wanted a slight variation, you could assign only 1 image to the first student (or victim ;-) . Each of the remaining students is assigned a date on which they must add one image (anything at all, as long as it furthers the storyline) to the shared story-space. This would be a way to spread out the activity, possibly less work for you.
But '5-card Flickr' has a nice ring to it & I expect anything designed by Cogdog to be solid. Whichever way you offered it, I think having a community building exercise at the beginning of a program is an excellent idea. You could engage a lot of learners with an activity like this & for sure it would be FUN.