Next week's new series opener features a mystery slime found on the bodies of a US Navy Sea, Air, Land Team commando and a beached walrus.
Significant amounts of alcohol are found in both cadavers.
Chief Medical Examiner Donald 'Ducky' Mallard wrestles with the forensics of the problem, telling Gibbs he suspects an alien sea monster.
'What makes you think that, Ducky?' Gibbs asks.
'Something weird's come over both of them,' Mallard replies, 'maybe a genetically modified sperm whale.
'They're absolutely notorious for liking a tight Seal.'