Lonely gray mouse Matthys is found by her chiropractor Dirk Van Gelder, murdered at home, the corps covered with a dress too small in size. The only lead is that she was called by Mr. Joosen's telemarketing firm, notably sole male operator Donald Blomme, a loner, who lies to cover up he met the victim. The MO fits an earlier case, from which the dress seems passed on. The team can't prove anything against the apparent model citizen, so they set up a trap with the female cop as bait.