We have a bona fide biotech soap opera going on these days. Spurned love. Possible romance. Disgruntled suitor. And, of course, the unknown villain. In this drama, though, the villains get caught before too many dastardly deeds can be done.

Romance in the air
Onyx Pharmaceuticals (UNKNOWN:ONXX.DL) is playing the role of the wanted damsel in this soap opera. Onyx spurned the amorous advances of Amgen (NASDAQ:AMGN) earlier this month. Amgen offered $120 per share for the biotech, but Onyx turned the larger company down to play the field.

Several companies appeared to possibly participate in a budding romance with Onyx. One, though, apparently threw the roses in the trash can early on. Word leaked out on July 18 that Pfizer (NYSE:PFE) decided not to move forward because the price was just too high. However, Pfizer has not made any public comments yet about a potential acquisition of Onyx, and some are still speculating that the company is still in the hunt.

So much for the "romance." What about the villains?

Vile villains
"Unknown traders" who knew about Amgen's offer before it was publicly announced began buying call options in Onyx starting on June 26 and kept on scooping up more calls through June 28. Many of these options were inexpensive out-of-the-money calls that require the stock to rise rapidly for the buyer to make a profit.

On Wednesday, June 26, abnormally high volumes of call options expiring on July 19 with strike prices of $95 and higher were bought. Onyx traded at around $84 per share at the time, so someone was banking on at least a 13% increase within a three-week period. Call option trading volumes at these strike prices increased over the next couple of days.

News about Amgen's offer to buy Onyx was first reported after the market closed on Friday, June 28. Onyx announced that it was rejecting Amgen's bid on Sunday. Shares in the biotech skyrocketed 51% the following Monday. The "unknown traders" were sitting on a tidy profit of $4.6 million deposited in foreign accounts. But not for long.

Justice prevails
The Securities and Exchange Commission tends to notice when unusual trading occurs right before a major event is announced by a public company. It didn't take them long to realize that mischief was afoot. On Wednesday, July 3, the SEC announced that it had frozen the assets of the traders. Michele Wein Layne, director of the SEC's Los Angeles office, referred to the perpetrators as "suspicious foreign traders."

Not only did the SEC freeze the assets of the villains, but the agency is pursuing further action to require the unknown traders to "disgorge their ill-gotten gains" (I love that dramatic wording), pay interest, pay financial penalties, don't do it again, and walk the plank. OK -- I made the last one up, but you get the picture.

Unfortunately, we still don't know who these suspicious foreign traders are. Any good soap opera leaves the viewer without all the answers, though. Some element of mystery must be left in the air.

Moral to the story
Unlike many of the soaps on TV, there actually is a moral to this story: Getting rich quickly doesn't (always) pay. Sure, our villains made millions in just a few days -- but they won't get to enjoy their riches.

The SEC is always watching out for unusual trading patterns. Anyone who thought that they could buy way out-of-the-money options just before Onyx revealed the Amgen offer and get away with it weren't thinking very clearly.

This same kind of story line has been repeated several times before. Just like in the soap operas.

Fool contributor Keith Speights has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.