The second newscast confirms that the killer whale pod that Ace has been investigating has been contaminated by a chemical.

Tracking the contaminant through the food web to salmon leads Ace to the Louisa M. Allsort Salmon Hatchery and lands him/her in the middle of a "Truth or Fish'n" game show (Activity 3). Ace gathers more knowledge and information about salmon as s/he tries to figure out which contestant is telling the truth.

Ace then meets with salmon specialist Dr. Caveh R., and together they discover which species of salmon are found in the area where the whales forage. However, Ace must test for contamination further up the food chain by locating the herring populations on which the salmon feed. A visit to Plankton Girl's trailer teaches Ace the significance of plankton to ocean life, and how to track herring populations by examining plankton blooms on satellite imagery. After taking the definitive Plankton Quiz, (Activity 4) Ace is able to identify the location of the plankton blooms and subsequently the location of the herring on a computer-generated map (Activity 5).

Back in the office, Ace's new computer helps to overlay the distribution maps of the killer whale pods, the salmon, the herring and the plankton. Through careful map reading, Ace is able to pinpoint the highest overlapping areas of contamination to the Wumba Chumba Islands. Ace must now travel to the islands as the search for the barrels heats up!