Gundobad and Godigisel were two brothers who were fighting each other to take each other's land. They were not Franks but Clovis kept encouraging them to fight probably hoping they would kill each other and then he would take both lands. Gundobad marched on Vienne, which was held by his brother, put it under a siege. When the stocks of food in the city began to run low, Godigisel, fearing there would not be enough for himself and he might have to miss a meal, rounded up a bunch of people that he considered superfluous and booted them out to be killed, enslaved, whatever.
One of the people, he kicked out was the city engineer; who was understandably pissed off. So, this fellow told Gundobad how he might sneak into the city through the aquaduct. He lead them personally through the system. Vienne fell to the besiegers. Almost everyone inside, except the Franks, was put to the sword, including Godigisel. The Germanic tribes were never very shy about kinslaying. This land became part of the Burgundy of the Nibelungs.
There is a lesson here. If you are the leader of a city that is being attacked, you should have a list of people who are too important to leave outside the city walls and make sure that none of the people on that list end up there. Or their families.
Clovis had social opportunities to mess with Godigisel's and Gundobad's heads since their niece, Clothide was his wife.
From Gregory Book II, section 33
Beatles' Song of the Week
Per fenestra latrinae intus venit,
Ab cocleare argentum protectus est,
Sed nunc eam pollicem sugit et errat,
Ad ripis ipse lacunae.
Dixitne eam aliquis?
Dies Solis Dies Lunae phonice vocat,
Dies Martis me phonice vocat.