Michael's old pal from graduate school comes for a visit. What Mike doesn't know is that Peter is a member of a radical group called Planetwatch and is in town as part of a revenge plot to plant a bomb on a yacht.
Lisa Ruddick, a journalist. uses a story on Jonathan's research as a ruse to gather damaging information on Jonathan's boss, the eccentric Baron Trent.
Mike's experiments using sound waves with the dolphins is a breakthrough in communications, but his boss Trent sees it as his chance to go in search of sunken treasure off the coast.
Larson's skeptical in-laws arrive for a visit, but when they see the kids are not too keen about their Australian environment, they decide to take them back to the States.
