What’s really going on at Nikola — an inside look at the truck maker mired in controversy

Inside Nikola — the one-time Wall Street darling mired in controversy

The last couple of months can only be described as a roller coaster ride for battery-electric and hydrogen-powered semi trucker maker, Nikola. On June 9, just a few days after it went public through a SPAC, Nikola's market cap briefly surpassed that of Ford, making its founder, Trevor Milton, a billionaire in the process. For a company that hasn't yet brought a product to market and has practically no revenue, the valuation raised some eyebrows. Still, a major deal with General Motors seemed to legitimize Nikola.

But only a few days later, Nikola's story began to unravel. Milton stepped down following a scathing report by short-selling firm Hindenburg Research that accused him of fraud. Later, CNBC reported that two women filed sexual abuse complaints against Milton. On top of that, Nikola is also reportedly being investigated by the DOJ and the SEC. And the deal with GM is uncertain.

CNBC visited Nikola's headquarters in Phoenix, Arizona to get a look at its Nikola Two hydrogen fuel cell truck prototype and to interview CEO Mark Russell about Nikola's future and the huge amount of controversy surrounding the company.