If I get airborne and receive a message about a suspicious device planted on the Aircraft from my company I WILL treat it seriously. Land ASAP would most likely be a priority whilst following the QRH. ( depending on the type of device and it's location, if known, whilst following the recommendations of the experts )
Accept the overweight landing if the runway is long enough, which it will be on the 777 even at max t/o wt we could stop the 777 in around 5000' if we tried.