*** (3 stars out of 5)
Hey, kids! Let's take a trip to the planet of the Trills! It's such a nice day out, so we'll spend it all in dingy caves or sterile hospitals.
Jadzia Dax discovers a talent for the piano, and becomes irritable enough to bang her head on the keyboard like a Sesame Street character. She's haunted by a spooky robed Mummenschanz with mask under mask under mask.
Is it delayed stress from her three years of endless tests at the Symbiosis Commission? The people who make the Japanese school system look like a Jamaican beach holiday? Prospective Trill hosts are rigorously examined. The accepted wisdom of modern Trill medicine is that an unsuitable host will kill both the slug and the meat puppet in a matter of days. But is that really the case?
The Guardians (unjoined Trills who spend their lives troweling mud in symbiont cave pools) are good with slugs. Not so great with going outside. Guardian Timor intuits that Dax's mental problem is with a previous host.
The Piano Man turns out to have been Joran Belar. Dax's fifth host died in a shuttle crash 86 years ago, and the six-month coma invented for the official record was really the short, tumultuous life of Joran Dax, Musical Murderer.
The Symbiosis Commission erased Dax's memory to cover the fact that slugs can ride wildly unsuitable hosts with no ill effects. Except if you include killing a guy as an ill effect.
If the secret gets out that Joran could host, well, why not EVERYONE? And there aren't enough worms for everyone. So the Trill government agrees to let Dax regain the memories if Sisko agrees to keep quiet. And Jadzia stops going on murder sprees with decrepit old Klingons.
"Equilibrium", a story about a government cover-up, and a repressed traumatic memory returning. Also an intriguing look at the weird world of lower brains and the wet-t shirt contests going on to win them. Or something.