When a film series enters the “IV” stage, the sequel usually requires an IV of Ringer’s lactate just to survive to its pitiful end. No so in “Star Trek IV: The Voyage Home” (1986). For non-Trekkies who endured a mediocre TV series and three equally pedestrian film reboots, the payoff here is the one thing “Trek” could always deliver when it wanted to – comedy (remember the Tribbles?). On a save-the-whales mission (there’s always a heavy-handed, moralizing theme), Kirk and the gang are fishes out of water (so to speak) in 1980s San Francisco (Spock’s a far-out dude). Time-warped hijinks ensue.