After training at the dolphin reconnaissance school, the dolphin Tristan was sent on an important mission to a secret military base of the USSR to obtain information about the Russians' new strategic weapon - a submarine that transforms into an airplane. After receiving a message that an unidentified object was discovered in Soviet territorial waters, moving towards a secret base, the Soviet command ordered to urgently send an experienced special agent, the dolphin Isolde, to intercept it.

Vasiliy Livanovas Colonel Yellow / commander Morzhov (voice)
Tatyana Dogilevaas Isolda Pavlova (voice)
Boris Bystrovas Tristan (voice)
Semyon Faradaas Henry / Greg (voice)
Vsevolod Abdulovas Forwarder / helmsman (voice)
Lyudmila Gnilovaas Crab (voice)
Nikolay Grabbeas Well-fed ship captain / truck driver (voice)
Efim Katsirovas lieutenant colonel Red / muskrat (voice)
Vladimir Prokhorovas John / Kremer / terrorist / captain / Morzhov / Yellow (voice)
Yuri Puzyryovas Vlas Afinogenovich Sukhoi / announcer (voice)
Kabul Rasulov
Aleksandr Chekhovskiy