The Netflix limited series "Death by Lightning" chronicles the compelling and tragic true story of James Garfield (portrayed by Michael Shannon), the reluctant 20th President of the United States, and his assassin, Charles Guiteau (Matthew Macfadyen). The four-episode drama delves into the lives of these two men: Garfield, an Ohio Congressman thrust into the nation's highest office, and Guiteau, an admirer whose increasingly severe delusions of grandeur led him to believe he was solely responsible for Garfield's political ascendancy. Guiteau's unraveling mental state ultimately culminated in him shooting the President, an act that, while not immediately fatal, led to Garfield's death from infection six months later, ending his brief presidency and resulting in Guiteau's execution by hanging.

In an interview, co-stars Michael Shannon and Matthew Macfadyen shared their insights into embodying these historical figures. Shannon found President James Garfield to be a remarkably admirable character, highlighting his intelligence coupled with genuine humility. "He was super intelligent, but not arrogant about it," Shannon noted, adding that Garfield used his intellect to "elevate all the people around him" rather than take advantage. Shannon admired Garfield's surprise at receiving votes, which he believed demonstrated a lack of overt ambition, prioritizing common sense and what was beneficial for the country. Macfadyen echoed this, praising Garfield's "great ability to listen."

Matthew Macfadyen described the experience of playing Charles Guiteau as complex and fascinating. He saw a "childlike quality" in Guiteau, who genuinely perceived himself as a hero despite his terrible actions. Macfadyen explained Guiteau's desire to be noticed, to feel important and productive, as a fundamentally "normal human thing." However, Guiteau's psychological instability led him to fixate on Garfield, convinced he was instrumental in his election. This delusion fostered a sense of betrayal when he was not granted a consulship, spiraling into the tragic events. Shannon drew a parallel to contemporary society, remarking that "This country is populated with Charles Guiteaus right now," referring to individuals driven by a desperate need to feel important and heard.

The actors also discussed the practicalities of portraying their characters. Macfadyen's portrayal of Guiteau included a subtle physical detail: making his hair appear "nice" despite its greasy reality and wearing clothes that were deliberately a little too big or ill-fitting, to underscore Guiteau's childlike and out-of-place nature. Shannon found that the period clothing, with its starchy vests and pinned garments, physically affected his movement, imparting a "certain bearing" appropriate for Garfield, a former military officer. The bond between Michael Shannon and longtime friend Shea Whigham, who plays Roscoe Conkling in the series, was also touched upon. Shannon lauded Whigham as a "dear human being" and a "journeyman" actor dedicated to his craft rather than Hollywood glamour.

A particularly poignant aspect of Garfield's story, as noted by Shannon, is the irony of his death from sepsis. Filming in Budapest, the birthplace of pioneering hygienist Ignaz Semmelweis, highlighted how preventable Garfield's death would have been with modern medical practices. Shannon expressed concern over similar "steps backward" in contemporary healthcare. Macfadyen recounted the "unsettling" experience of filming Guiteau's gallows scene, emphasizing Guiteau's performance for the crowd until the very last moment when the stark reality of his impending death dawned on him. Macfadyen also praised Betty Gilpin's performance as Lucretia Garfield, particularly in a memorable scene where she confronts Guiteau, threatening to erase him from history – a fate anathema to Guiteau's desperate need for recognition.