The Mortal Instruments (series) The Mortal Instruments is a series of six young adult fantasy novels written by Cassandra Clare, of which five have been published so far.
The Mortal Instruments is chronologically the second series of a proposed five in The Shadowhunter Chronicles. Publication history[edit] City of Heavenly Fire will be the last installment of The Mortal Instruments. The Infernal Devices by Cassandra Clare. The Mortal Instruments by Cassandra Clare.