Oh no, the Phantom has kidnapped Christine Daaé and is about to force her into a marriage with him. Raoul, the vicomte de Chagny, is anxious to stop this, and
make Christine marry him instead return freedom to Christine. The Persian, an old acquaintance of the Phantom, is also determined to stop the Phantom's terrorism of the Opera house, and to save Christine from a forced marriage, joins in with Raoul.
The Phantom hid Christine inside his house on the lake under the Opera house, well guarded. Can you help the duo break through all the defences to save Christine? We know that the Phantom, like any other crypto nerd, likes prime numbers...
The pressure is on. Solve these problems!