The literary slush pile — the manuscripts that writers send cold to agents and publishers — can yield treasure. Philip Roth, Stephenie Meyer and Judith Guest were all found there by executives knowing that an unsolicited manuscript could well contain the next writing sensation. Dublin-born author Rachel Ryan is the latest author be pulled from relative obscurity and touted as a writer to keep an eye on in 2021. After signing with super-agent Marianne Gunn O’Connor — who also represents Shane Hegarty, Cecelia Ahern and Pat McCabe — Ryan soon signed a deal with Simon & Schuster in Canada for her striking debut, Hidden Lies (called