Release Message:  As an attempt is made to hook Romana on vraxoin, the Doctor (Tom Baker) discovers a mystery man aboard ship to whom he gives chase.

Description:  The unstable interphase of the two ships opens up unexpected passageways for dangerous monsters caged in an electronic zoo aboard the cruise ship to escape. Meanwhile, as an attempt is made to hook Romana on vraxoin, the Doctor discovers a mystery man aboard ship to whom he gives chase.