Keller’s Fedora by Lawrence Block is a Kindle Single stand-alone mystery short story. Published in 2016 it follows Keller (his real name) as he reverts to a long ago profession of hired assassin. He had pretty much retired from that type of work and had settled down with his wife (who knew he was an assassin) and his daughter (who didn’t know). The money he had saved from his assassin jobs allowed him to pursue his current love, stamp collecting.