What was Wyatt's Rebellion?

In early 1554 a rebellion against queen Mary I broke out over fears that her impending marriage to Philip II of Spain would plunge England into becoming nothing more than an extension of Spain. This rebellion has become known as Wyatt’s rebellion, for one of its key architects was Thomas Wyatt the younger. The rebellion would end in failure, but what actually was it and who was involved, how serious was the threat against Queen Mary and why was its biggest casualty Lady Jane Grey, despite her not being remotely involved?