The first two plays in Tom Stoppard’s mammoth Coast of Utopia trilogy, Voyage and Shipwreck, were exciting intellectual mini-epics. Salvage should be where the cycle blows up even bigger; instead, it plays like a long anticlimax. Herzen (Brian F. O’Byrne), our Russian thinker-hero, lost his wife and child in Shipwreck; in Salvage (note the passiveness of even the title), he merely starts an underground newsletter. For the first time, Stoppard’s stuffed writing feels small alongside the wondrousness of Jack O’Brien’s still-grand staging. Catch the marathon, or else skip part 3.