The Black Lotus (Unabridged ed)

Ghost, Cormac and Kate are not like other kids...Ghost can turn invisible, Cormac can run up walls and Kate can talk to animals; all abilities which make them perfect recruits for the Black Lotus, a training school for ninjas.

But when the Moon Sword, a source of unimaginable power, is stolen by a samurai, the three are forced to put their new skills to the test in sixteenth-century Japan.