By Vern Thiessen. Directed by Donna Spencer. A Firehall Arts Centre and Gateway Theatre coproduction.

At the Firehall Arts Centre until January 29 and the Gateway Theatre from February 4 to 19

I'm grateful for Einstein's Gift, but I wish the package were a little less lumpy.

The subject is fascinating, and so are the themes that emerge from it. Edmonton playwright Vern Thiessen examines the world-altering, deeply conflicted life of German chemist Fritz Haber. Haber was Jewish but converted to Christianity to advance his career. He co-invented the Haber-Bosch process, which produces nitric acid and revolutionized the manufacture of agricultural fertilizers, saving millions from starvation. He also oversaw the use of chlorine gas as a weapon by Germany at Ypres in the First World War. His first wife Clara, who was also a chemist, subsequently committed suicide. Haber won the 1918 Nobel Prize for chemistry for synthesizing ammonia. The Nazis used Zyklon B, a pesticide he developed, in the gas chambers.

This is incredibly rich source material, and especially as he explores the exchanges between Haber and his colleague Albert Einstein, Thiessen develops a stimulating meditation on the relationships between applied and pure science, faith and nationalism, imagination and knowledge.

The first act works particularly well because this potentially abstract discussion is firmly rooted in the human dynamics between Haber, Einstein, and Clara. I began to tire of the debate about whether or not scientists should work toward specific practical goals. Still, there's a prickly, witty affection between the two men, and their stories carry the genuine weight of tragedy: Haber betrays himself for a state that betrays him; Einstein, the pacifist, sets the atom bomb ticking.

David Adams brings humble warmth to his performance as Einstein, and he fully exploits the lyricism of Thiessen's text. In Kathleen Duborg's reading of Clara, every line contains layers of subtle meaning. Relaying the myth of a constellation's creation, she says the word virginity and it shimmers with a combination of frailty, flirtatiousness, and vitality.

Unfortunately, Clara kills herself at the end of Act 1 as the play's first and most compelling story climaxes in the use of chlorine gas. At the beginning of Act 2, the play loses focus. Haber meets his second wife, Lotta, and heads off to failed experiments in the South Seas, but it feels like the script is covering biographical ground as opposed to telling a thematically coherent tale. Besides, Lotta isn't as compelling a character as Clara, and Sarah Donald's performance in the role is self-conscious.

I had trouble with Ron Halder's Haber throughout. I sensed that there was an interesting emotional performance--defensive, confused--going on beneath the surface, but Halder overacts and his vocal delivery is mannered. He's too loud too often and almost always sounds as if he's strangling on rage. Raugi Yu chews the scenery with even less restraint in a number of supporting roles.

On the other hand, Daniel Arnold, who plays Haber's assistant, Otto, offers a charmingly understated and nuanced portrait.

Phillip Tidd's set, a series of platforms covered in equations, seems to float the play on ideas. More often than not in this script and this production, those ideas come to engaging life.