(FORTUNE Small Business) – Oh, What a Heart-Thumping Ride: A 2,000% STOCK run-up, more than a quadrupling of profits, and the kind of marketing buzz—such as an appearance in Meet the Fockers—that other companies only dream of. Through the entrepreneur's lens, last year belonged to Taser International, the top performer on FSB's elite list of fastest-growing companies. But performance can be even more fleeting than Hollywood fame, and Taser's rapid growth—all based on its line of nonlethal stun guns—was zapped earlier this year. Reasons: concerns over product safety, questions from Arizona's attorney general, and an informal inquiry by the Securities and Exchange Commission. And oh, yes, a slew of shareholder lawsuits pertaining to all the above.

Pounded by that "perfect storm," as president Thomas Smith (his brother Rick is CEO) puts it, the stock dropped 76% from its Dec. 29 peak of $32.59 a share. One more big wave hit the decks in April, when Taser management filed for an extension on its 10-Q quarterly earnings report and noted that it was restating its 2004 financials. "That was a negative," says Sid Parakh, an analyst at Robins Group, a small-cap research firm in Portland, Ore., who suspended his rating on the stock. Taser filed the revised numbers in mid-May, reducing last year's earnings per share by 1 cent. Soon after, Joseph Blankenship, an analyst at Source Capital Group, raised his rating from sell to hold, figuring the worst was over. Still, the company retained its popular standing (37th place of all Nasdaq stocks) among short-sellers, Wall Street's doomsayers.

Faced with all this trouble, plus a major push by Amnesty International to rouse opposition to the Taser, the company's new offices in Scottsdale now brim with suspicion. "We've been the victim of a media frenzy of misinformation," Thomas Smith said on an investor conference call in April. (Much of the negative press concerns claims that Taser stun guns may be lethal when used on suspects with certain health problems.)

But the momentum of 2004 is not completely undone. While no one can say when or how the SEC inquiry will evolve—the SEC would not comment on the matter—none of its known probes appear to threaten the company's survival. Arizona officials questioned some Taser executives earlier this year; the officials aren't talking—the company says they asked about the civilian version of the gun—but they are pursuing neither action nor inquiry. The company is catching flack on the consumer front, where it sells a civilian version of the Taser over the Internet ($999). California is currently considering legislation to ban such sales. But the company's products continue to get approving nods from such institutions as the U.S. Department of Defense and Britain's Home Office, both of which have tested versions of the Taser for military and law enforcement uses. "That's our bread and butter," says Smith. The Taser's usefulness in law enforcement was widely exhibited late in May, when Atlanta police zapped and then subdued a murder suspect who was perched on a crane for more than two days.

Sales to government organizations fueled a compound growth rate of 111% in revenues over the past four years, and while the domestic market still has plenty of room to grow—only 13% of U.S. police departments make the Taser standard issue to officers—even bigger markets may lie overseas. "International is eight times the size of the U.S. law enforcement market," says Smith. Several countries, such as Canada and Singapore, already employ the Taser. A couple of competing products now on the horizon could cut into Taser's sales, but it will take time for them to match Taser's independent research. So when might Taser get back on a high-performance track? "It's going to take a while," Smith concedes, and he points to the need for resolution of the SEC inquiry and for further dissemination of independent studies supporting Taser's safety record. Sales and earnings were down sharply in the first quarter of 2005 as potential new customers held back. In early June the stock had recovered from its April low of $7.64 per share to a more respectable $11.35. —JOHN J. CURRAN