Is it possible to make a shader which is transparent but when viewed behind an object it displays a silhouette in colour/texture.

can anybody help me with this. the idea is having a creature that you can't see unless its behind an object.

I've been looking at this for a while now. I've found people who have made the 2 parts of this idea, but not working together. so having a normal object, been able to see a coloured silhouette or a textured silhouette of it through objects. but I've never been able to make a transparent object to have this effect.

( if you have a solution to this, please reply with the code, would help allot)