Reversed Regeneration

The TARDIS decides to take the Doctor to Cardiff so she can refuel. Refusing to let the Doctor back in, until she has finished re-charging. With the Doctor, Amy, Rory and River stranded in Cardiff the Doctor try's very hard not to run into any old friends, unfortunately though, that lasts only about a minute.

With a confused Torchwood team and a curios TARDIS crew the Doctor and Jack have quite a bit of explaining to do, but unfortunately for them, it gets cut short by an unexpected visitor who just so happens to have brought something with him. The unknown figure uses the Master's old laser screwdriver to turn back time on the Doctors regeneration cycle, resulting in a 5 year old Doctor.

It's then up to the Torchwood team and their new guests to look after the young doctor until they can figure out how to fix it. But how hard will it be looking after a 1000 year old timelord in a 5 year old body really be? Especially when a few old friends and possibly enemies, come to visit too?