On Jan. 9, Kate Middleton will celebrate her 38th birthday, which will likely leave some royal fans wondering how the Duchess of Cambridge will be spending the upcoming day. Now, a new report has shed some light on what Prince William has secretly planned to do to mark the occasion.

According to Life & Style, the Duke of Cambridge is "planning a mini birthday getaway" that the couple will go on with their three children, Prince George, Princess Charlotte, and Prince Louis.

"Now William wants to whisk their family away from it all on a no-expenses-spared trip to Mustique as a surprise for Kate," a source revealed to the publication. As for the planned accommodations, the property that is reportedly being considered is a "$15 million, seven-bedroom mansion with an infinity pool, private chef, screening room, gym and tennis court."

However, the Prince is also said to be putting some emphasis on getting a bit of alone time with the Duchess of Cambridge as well. "William wants to ensure they get quality time as a couple, so he's organizing spa treatments, a diving trip and surfing lessons for two," the insider added.

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Additionally, the outlet said that William believes this trip could be a great way to start off 2020 as 2019 has been "a tough year" for the couple. Earlier this year, William and Kate were faced with a new future for The Royal Foundation when Meghan Markle and Prince Harry decided to forge their own charitable path. This reportedly resulted in Kate unexpectedly taking a specific trip to "collect her thoughts."

The separation was also accompanied by persisting rumors of a feud between the Fab Four throughout the year. However, some have speculated that Meghan and Kate may be forced to work together and "step up" at the start of 2020 as they begin to look to the future.

Prince William and Kate Middleton
Prince William and Kate Middleton engage in a walkabout in Ballymena town centre on Feb. 28, 2019 in Ballymena, Northern Ireland. Getty Images/Charles McQuillan