In the words of The Daily Telegraph, the decision by the Brexit Secretary and at least one fellow minister to quit has plunged Theresa May's political future into doubt. Friends of David Davis tell the paper his resignation was "sad but principled" - because the minister believed he had to take a stand "in the national interest".
The Daily Mirror says the departure comes at a time of "open warfare" with dozens of Tory MPs furious at the plan which could keep the UK closely tied to Brussels now plotting to oust the prime minister.
Eurosceptic MP Andrea Jenkyns, quoted in The Financial Times, says she "takes her hat off" to Mr Davis and his resignation should become a "game-changer for Brexit". Labour party chairman Ian Lavery tells The Daily Express the country can't "go on like this", insisting "Britain needs a functioning government".
In The Guardian, the head of counter-terrorism policing, Neil Basu, says the death of Ms Sturgess will only strengthen his resolve to bring those responsible to justice. The Times says the death of a British citizen by Novichok comes as President Trump and the rest of Nato prepare to meet in Brussels this week, to discuss countering Russian aggression.
Coverage of the operation to rescue 13 members of a youth football team trapped in a flooded cave in northern Thailand dominates many Thai newspapers. "Four out, nine to go," runs a headline in The Bangkok Post. The Pattaya Mail says the people of Thailand have been gripped by the ordeal faced by the boys and their coach and their plight has made global headlines.
Finally, a photograph in The Daily Mail shows a field of lavender blooms, in rolling countryside, basking beneath a perfect blue sky. The paper notes that the scene wouldn't look out of place in Provence or Tuscany, but the image was taken in North Yorkshire, where the lavender is thriving in the continuing heatwave.
Separate photographs in The Telegraph show how the warm weather is also revealing historical secrets; a Roman-era fort, crop markings and the lost outline of a World War II airfield, situated in scorched fields, have all become visible from the air.
The Sun says England had its warmest day of the year on Sunday, a high of 32.4C in Gosport, exceeding the temperature in Barbados.