Czech bass player Pavel Jakub Ryba formed his trio Mind the Step back in 1990, and the group released its first CD soon after. Based in Kutná Hora, they played Prague only occasionally, appearing more often in jazz clubs and festivals throughout Europe.

Then, nine years later, a miracle happened.

P.J. Ryba and Mind the Step suddenly got remarkable exposure in the West for their self-released second album, Yes, Yes, No, No, which sat at the top of the U.S. jazz charts for three months. A glowing review by Paula Edelstein in Jazziz Magazine was the catalyst for this Cinderella story. She wrote: "He is an amazing artist. As one of the leading personalities of Czech jazz, P.J. Ryba is a star."

From a perspective closer to home, Edelstein is only partly right. It's true that P.J. Ryba is an amazing bass player, but he isn't "a star," at least on the Czech jazz scene. Maybe Ryba, who is 44 but looks 10 years younger, isn't as famous as he should be because there are already two world-famous Czech jazz bassists: George Mraz and Miroslav Vitous, who are among the most respected players in modern jazz. Their influence on the Czech jazz scene is a strong one, though in Ryba's view, "Everyone is playing the same kind of jazz [here]. There's not much originality."

Most of the younger jazz bands nowadays just want to get funky, but P.J. Ryba and Mind the Step don't go there. Ryba says he is most influenced by the 1970s fusion group Weather Report, especially its period with fretless bass player Jaco Pastorius. (Miroslav Vitous was the original bassist in this seminal band.)

Mind the Step combines fusion, straight-ahead and free jazz with a highly original flair. On the opening track of their most recent CD, Morally Topless (2004), the group slowly builds the tension around a luxurious groove — then they take it way outside. "Tough Talk," originally a soul-jazz song by the Jazz Crusaders, is a terrific or terrifying opener, depending on how you like your jazz. This opener, however, is appropriate for a band whose name itself is a clear warning to new listeners. Later on the CD, Mind the Step creatively reinterprets the classic "Straight, No Chaser," by Thelonius Monk. Never mind that the group doesn't have a pianist — they pull it off admirably.

The core of Mind the Step consists of Petr Albert Venkrbec (alto sax), Jiří Kollman (percussion) and Ryba. On Morally Topless, the trio is joined by well-known fusion guitarist Mike Stern. Ryba explains how this came about: "We got in touch with Mike in New York, when we were playing the Knitting Factory. We went down to the 55 Bar to see his gig, had a word with him, and next time he was over here we grabbed him and recorded the stuff."

For their upcoming show at the Castle, Mind the Step will be joined by the widely acclaimed British trumpeter Bryan Corbett. "We met him at one of the British festivals," Ryba says. "We liked his tone range and invention. The rest is the same as with Stern — we had a word there, phoned each other later, and now he's coming."