The Mortal Instruments: City of Ashes

The Mortal Instruments: City of Ashes was a planned film adaptation of the same name, serving as a sequel to The Mortal Instruments: City of Bones. It was to be the second in a planned film series adaptation of The Mortal Instruments series of novels by Cassandra Clare.

Plot
Clary returns to the Institute and must help her brother Jace clear his name when he is accused of being in league with Valentine.

Why It Was Cancelled
The first film only recouped half of its budget, marking it only a moderate box office hit.

Result
Plans for the sequel were dropped and the entire franchise was rebooted as a TV series, Shadowhunters.