Danger Down The Nile by James Patterson is the 2nd book in the Treasure Hunters series and was written with Chris Grabenstein and illustrated by Juliana Neufeld.
This story was released on September 1, 2014.
Danger Down The Nile book description
Bick Kidd and his globe-trotting siblings Beck, Storm and Tommy may have completed their first treasure hunt after their father was lost at sea, but their kidnapped mother is still in the hands of nasty pirates.
Their search for a rescue plan takes them down the Nile river in Africa, where they’ll have to navigate everything from Egyptian pyramids in the desert to wet-and-wild jungles – not to mention life-threatening encounters with wilderness diseases, angry hippos and some seriously bad guys – in order to find the treasure and save the day.