At the conclusion of “The Germans in Paris,” Jonathan Leaf’s engaging new play about the friendship between Heinrich Heine and Karl Marx, Heine tears a huge strip of paper off the wall to show a column of sepia portraits of his friend, graffitied over with a great red “Revolution.” He then directs a humanist rebuttal of socialism at the mute images, elegantly damning Marx’s doctrines for their joylessness and insensibility to beauty.

This moment encapsulates the Immediate Theater Company’s production of Mr. Leaf’s play: deftly realized and packed with ideas, but opaque in terms of its specific message and purpose.

The subject of Mr. Leaf’s play is tantalizing: For a brief period in the early 1840s, Heinrich Heine, the iconic German Romantic poet, and Karl Marx both lived in Paris, became “friends and allies,” and produced a radical magazine together. Into this already heady mix Mr. Leaf throws the awkward and pompous Richard Wagner, spouting casual anti-Semitism and hoping to work his way into Paris’s boudoirs and opera houses.

Plays like “Copenhagen” and “Travesties” revel in revisiting fecund intellectual intersections, and Mr. Leaf is up to the difficult task of humanizing and humorizing these men. The play is shot through with light wit (as when Marx, in prison, notes that the debtors have already embraced him as a savior) and, until its final moments, it never staggers under the weight of its characters’ genius. Mr. Leaf makes the period his own, but he is intellectually responsible enough to keep the comparatively ignorant (ahem) aware of when he’s putting his own spin on things.

The play’s faults are far simpler. At the outset, Marx is arrested after confiding to Heine his suspicion that there is an informer amongst his followers. This promising start peters out, however; after introducing its primary players, the script wanders. Some rambling scenes could have been sharper; others don’t seem necessary at all. The result is confusion about which of its many subjects the play is about, at the most straightforward dramatic level.

Jose Zayas’s svelte production glides along nicely. The bare space is filled with several stacks of books, cleverly manipulated to form necessary furniture. Kevin Kelly’s Heine is a well-drawn contradiction, an elegant machiavel whose sympathy with Marx is earnest. Corey Moosa’s Marx is suitably explosive, and Bruce Barton shines as Conrad Schramm, Marx’s ardent secretary, showing fiery ideological passion in the face of Heine’s measured cool.

In the play’s final scene, Heine expresses the idea that writing is never improved by quantity. Mr. Leaf should take his character’s advice to heart, but in the meantime this sharp production shows he has more than his fair share of ideas to work with.