On the origin of the extended infrared shell around NGC 6888 . ... The results of a complex program of research on the extended infrared shell around the nebula NGC 6888 and the star WR 136 are presented. We performed H a observations with a Fabry-Perot interferometer mounted at the focus of the 125-cm telescope and radio continuum (2.7 cm to 31 cm) and 21-cm HI observations with the RATAN-600 radio telescope. ... Curve passages in H I line through area NGC 6888. ...