Willy was invited to help investigate strange goings on - several ships had been attacked by what seemed to be a sea monster. Willy, Romy, Rigadon and Tico went, although soon the ship they were on was invaded and they, alongside Ned the harpoonist (very like Hans from the previous story) and another Professor, were kidnapped by the mysterious Captain Nemo. After having adventures under the sea, they finally escaped