The Grimoire of the Lamb (The Iron Druid Chronicles, #0.4)

There's nothing like an impromptu holiday to explore the birthplace of modern civilisation, but when Atticus and Oberon pursue a book-stealing Egyptian wizard - with a penchant for lamb - to the land of the pharaohs, they find themselves in hot, crocodile-infested water.

The trip takes an even nastier turn when they discover the true nature of the nefarious plot they've been drawn into. On the wrong side of the vengeful cat goddess Bast and chased by an unfathomable number of her yowling four-legged disciples, Atticus must find a way to appease or defeat Egypt's deadliest gods - before his grimoire-grabbing quarry uses them to turn him into mincemeat.