Nightspark

The rousing, magical sequel to Ghostcloud, set on the waterways of a richly reimagined London.
Michael Mann returns for the riveting sequel to Ghostcloud!
Several months after the ghosts freed the children of Battersea and uncovered Tabatha Margate's sinister experimentation on ghostclouds and cloudghouls, Luke Smith-Sharma struggles to divide his time between learning the ropes of being a ghostcloud and studying to become a detective. 
But not everyone made it out of the power station, and as he tries to adjust to "normal" life by pursuing his dreams, the guilt over his friends left behind is eating Luke alive. 
When a seemingly new threat emerges, Luke's investigations will take him far beyond the borders of London, forcing him to face his past and confront his deepest fears to try to save Ravi, the friend who was there for him in his darkest hours.
With the help of several unexpected allies, Luke and his friends—ghost-girl Alma and human Jess—embark on a new, thrilling adventure as they work together to find Ravi and to finally thwart the evil Tabatha Margate's plans once and for all!