After being put back to sleep and abandoned in an old museum, Slappy is brought to life by a curious girl on a school trip. Out for revenge, Slappy uses his powers to raise an army of creatures from the exhibits. But when the museum closes, Slappy and his new friends are locked inside with Arragatis, an ancient mummy with his own plan for revenge. It's dummy versus mummy as Slappy faces his most dangerous and frightening opponent yet! Can Slappy defeat...

The mummy of King Tut's grandmother is the main attraction at the Fogville museum, but Echo the bat and his human friends, the Bat Pack, discover that at night she is rising from her sarcophagus--can they find a way to bring peace to this restless mummy?