Way back when revolutions was the think, bombs were Robin Abbott and Skip Gibbs's bag - until their explosive ''freedom of expression'' was curtailed by some considerable prison time. Now the ex-SDSers are back out in the material world and looking to put their pyrothecnic skills to more profitable use. Theor target is Woody Ricks, dope-addled Detroit ''rich kid'' and aging former fellow radical who Robin thinks ratted them out to the Feds. But Motown cop Chris Mankowski also has his eye on Woody - albeit for another matter entirely - and until his recent switch to Sex Crimes, Chris was the Bomb squad's golden boy. So it's only fitting that he'll be around when the really nasty stuff starts going down...or blowing up.