Robbie Williams reportedly rang Joss Stone to comfort her after hearing about the plot to kidnap and murder the singer.
The Take That star invited Stone to the band's gig in Cardiff on Thursday, according to British tabloid, The Sun.
A source said: "Robbie and Joss have been mates for years. He got straight on the phone to see if she was OK and invited her to Wales.
"She's still in shock but Robbie did his best to put a smile back on her face. His cheeky chappy side was in overdrive when they met up after the gig.
"She was making light of it too, joking that it's been like an episode of 'Midsomer Murders'."
Two men have been charged with conspiracy to rob and cause grievous bodily harm after being arrested near Stone's Ashill home on Monday.
Notes were found in a car nearby allegedly outlining plans to "rob and kill" the singer and to "find a river to dump her in".