Susan collis & her colleague jess turner are employed by the ministry of defence in london. they are sent to sweden ostensibly to advise on the training of female recruits. due to the duplicity of mi6 they are not warned that the training camp where they are to be based appears to be a source of illegal arms for terrorists. however they receive a warning of the dangers that they face, from an anonymous source in sweden. the information they receive not only saves their lives but enables them to close the source of the illegal arms. how the arms were getting from sweden to the terrorists proves to be a much more intractable problem; which they solve but only with the aid of the combined efforts of gchq and mi5. the disappearance of their anonymous source leads them back to sweden and unexpectedly back into the criminal organization that was involved in the illegal weapons trade. the matter is resolved by their locating the mysterious source which then provides an unexpected bonus for british intelligence.