The beautiful Ulla features strongly in this double header while Sandy is away on a camping trip so rare episodes not featuring Luke Halpin. She brings Porter into the loop concerning an experimental naval dolphin into which the Navy has, or will, pour a $1million and the dolphin has flipped.
Porter suggests time in their pen at Coral Key with Flipper and at first it seems to work. Ulla and some naval ratings are able to put a harness with yellow float on "Tough Guy" but suddenly he breaks the pen gate and makes a swim for it.
After Flipper, Bud and Porter fail to find Tough Guy, Porter searches the park in the launch, Bud and Flipper the coastal inlets in the skiff and the navy have a cutter and helicopters combing the open ocean along with the Coast Guard. Bud even admits to missing Sandy and his help.
There is a lot of repetitive search footage. Ulla finally finds TG and shoots him with a tranquilizer dart but it falls out and he escapes again. TG now heads to shore but the yellow buoy is trapped in the mangrove swamps where alligators roam. Whilst most of the searchers take a lunch break, Flipper carries on, locates TG, frees him from the mangrove roots and tows him back to the Ricks'.
It turns out all this experience was all it took to snap TG out of it much to the joy of Ulla, the navy and their project.