This was for Batman: Legends of the Dark Knight #50. As I've probably mentioned elsewhere, these pin-ups were usually wide open, with an editor calling up and asking for a drawing but leaving it to the artist to come up with an idea. I don't know where this one came from. I think I just started sketching Batman standing there and the other elements started to appear. I remember Archie Goodwin commenting on the mouse in the trap and Robin's expression.